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Convert rational numbers to decimals

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5106617
Evaluate each expression mentally. Convert between fractions and decimals when it makes the calculation easier. a) \(0.25 + \frac{1}{2}\) b) \(0.4 - \frac{3}{5}\) c) \(0.75 - 1\) d) \(1.1 + \frac{9}{10}\)

Hints

- Convert each fraction to a terminating decimal. - Predict whether the difference should be positive or negative. - Choose one representation for the two values in each expression.

Solution

1. For a), \(\frac{1}{2} = 0.5\), so \(0.25 + 0.5 = 0.75\). 2. For b), \(\frac{3}{5} = 0.6\), so \(0.4 - 0.6 = -0.2\). 3. For c), \(0.75 - 1 = -0.25\). 4. For d), \(\frac{9}{10} = 0.9\), so \(1.1 + 0.9 = 2\).

Answer

a) \(0.75\) b) \(-0.2\) c) \(-0.25\) d) \(2\)
5106827
Lucas and Mia evaluate \(0.125 + \frac{3}{4} + 0.25 + \frac{1}{8}\) in different ways. Lucas converts the fractions to decimals. Mia converts the decimals to fractions and rearranges the addends. Carry out both methods. Which method seems more efficient here? Explain.

Hints

- Convert only values whose equivalents you know exactly. - Look for pairs that combine to a whole number. - Rearranging addends does not change their sum.

Solution

1. Lucas’s method: \(\frac{3}{4} = 0.75\) and \(\frac{1}{8} = 0.125\). Then \(0.125 + 0.75 + 0.25 + 0.125 = 1.25\). 2. Mia’s method: \(0.125 = \frac{1}{8}\) and \(0.25 = \frac{1}{4}\). Then \(\frac{1}{8} + \frac{3}{4} + \frac{1}{4} + \frac{1}{8}\). 3. Regroup: \(\left(\frac{1}{8} + \frac{1}{8}\right) + \left(\frac{3}{4} + \frac{1}{4}\right) = \frac{1}{4} + 1 = 1.25\). 4. Both methods are efficient. Mia’s grouping immediately creates a whole number from the fourths.

Answer

Both methods give \(1.25\). Mia’s method is especially efficient because \(\frac{3}{4} + \frac{1}{4} = 1\).
5106837
Evaluate \(\frac{5}{6} + 0.4 + \frac{1}{6} + 1.1\). Decide whether to convert every value to fractions or decimals, or to combine compatible terms separately. Briefly justify your choice.

Hints

- Consider whether each fraction has a terminating decimal representation. - Look for fractions that add to a whole number. - A common representation is not always necessary for every term at once.

Solution

1. Converting the sixths to decimals would create repeating decimals, so keep them as fractions. 2. Group the fractions: \(\frac{5}{6} + \frac{1}{6} = 1\). 3. Group the decimals: \(0.4 + 1.1 = 1.5\). 4. Add the partial sums: \(1 + 1.5 = 2.5\).

Answer

Combine the fractions and decimals separately. The value is \(2.5\).
5106887
Evaluate the expression efficiently. \(\frac{2}{5} + 1.35 - \frac{3}{4} + 0.1\)

Hints

- Both fractions have terminating decimal representations. - Convert to one representation before combining terms. - Look for decimal pairs that are easy to add or subtract.

Solution

1. Convert the fractions to decimals: \(\frac{2}{5} = 0.4\) and \(\frac{3}{4} = 0.75\). 2. Substitute: \(0.4 + 1.35 - 0.75 + 0.1\). 3. Group efficiently: \((0.4 + 0.1) + (1.35 - 0.75) = 0.5 + 0.6 = 1.1\).

Answer

\(1.1\)
5106927
Let \(T = 0.8 \cdot \frac{5}{4} + 0.25\). a) Evaluate \(T\) in two ways: 1. Convert every number to a decimal. 2. Convert every number to a fraction. b) Which method is more efficient for this expression? Explain.

Hints

- Convert \(\frac{5}{4}\) to a decimal for the first method. - Convert both decimals to fractions for the second method. - Look for reciprocal factors.

Solution

1. Decimal method: \(\frac{5}{4} = 1.25\), so \(0.8 \cdot 1.25 + 0.25 = 1 + 0.25 = 1.25\). 2. Fraction method: \(0.8 = \frac{4}{5}\) and \(0.25 = \frac{1}{4}\). Then \(\frac{4}{5} \cdot \frac{5}{4} + \frac{1}{4} = 1 + \frac{1}{4} = \frac{5}{4}\). 3. The fraction method is especially efficient because the reciprocal factors cancel immediately.

Answer

a) \(1.25\), or \(\frac{5}{4}\) b) The fraction method is more efficient because \(\frac{4}{5} \cdot \frac{5}{4} = 1\).
5128377
Which fraction has the same value as \(0.625\)? Check each option by converting it to a decimal. \(\frac{625}{100}\), \(\frac{5}{8}\), \(\frac{3}{4}\)

Hints

- Convert each fraction to a decimal. - You can divide the numerator by the denominator. - A decimal with three places can be written as a fraction with denominator \(1000\).

Solution

1. Convert \(\frac{625}{100}\): \(625 \div 100 = 6.25\), so it is not equal to \(0.625\). 2. Convert \(\frac{5}{8}\): \(\frac{5}{8} = \frac{625}{1000} = 0.625\). 3. Convert \(\frac{3}{4}\): \(\frac{3}{4} = \frac{75}{100} = 0.75\). 4. Therefore, \(\frac{5}{8}\) is equivalent to \(0.625\).

Answer

\(\frac{5}{8}\)
5152267
Convert each value to the requested form. If a decimal is given, write it as a fraction in simplest form. If a fraction or percent is given, write it as a decimal. (1) \(\frac{7}{25}\) (2) \(0.08\) (3) \(1\frac{3}{4}\) (4) \(12.5\%\) (5) \(0.375\)

Hints

- For some fractions, rewrite the denominator as \(10\), \(100\), or \(1000\). - A percent is a number divided by \(100\). - To simplify a fraction, divide the numerator and denominator by a common factor.

Solution

1. Multiply \(\frac{7}{25}\) by \(\frac{4}{4}\): \(\frac{7}{25} = \frac{28}{100} = 0.28\). 2. Write \(0.08\) as \(\frac{8}{100}\), then simplify: \(\frac{8}{100} = \frac{2}{25}\). 3. Convert the mixed number: \(1\frac{3}{4} = 1 + 0.75 = 1.75\). 4. Divide by \(100\): \(12.5\% = 0.125\). 5. Write \(0.375\) as \(\frac{375}{1000}\), then simplify: \(\frac{375}{1000} = \frac{3}{8}\).

Answer

(1) \(0.28\) (2) \(\frac{2}{25}\) (3) \(1.75\) (4) \(0.125\) (5) \(\frac{3}{8}\)
5104037
Convert each fraction to a decimal. Round to the nearest hundredth when necessary. a) \(\frac{3}{4}\) b) \(\frac{5}{6}\) c) \(\frac{12}{5}\) d) \(-\frac{7}{9}\)

Hints

- Interpret the fraction bar as division. - If the decimal does not terminate, identify the digit that determines rounding to the nearest hundredth. - Use \(\approx\) for rounded values in your work.

Solution

1. For a), \(3 \div 4 = 0.75\). 2. For b), \(5 \div 6 = 0.8333\ldots\), which rounds to \(0.83\). 3. For c), \(12 \div 5 = 2.4\). 4. For d), \(-7 \div 9 = -0.7777\ldots\), which rounds to \(-0.78\).

Answer

a) \(0.75\) b) \(0.83\) c) \(2.4\) d) \(-0.78\)
5104047
Convert \(\frac{7}{8}\), \(1\frac{2}{3}\), and \(-\frac{13}{11}\) to decimals. Use repeating-decimal notation when needed. Which values have terminating decimal forms?

Hints

- Rewrite a mixed number as an improper fraction before dividing. - Look for a repeating remainder in the division. - A fully simplified fraction terminates only when its denominator has no prime factors other than \(2\) and \(5\).

Solution

1. Divide to convert \(\frac{7}{8}\): \(7 \div 8 = 0.875\), which terminates. 2. Rewrite the mixed number as \(1\frac{2}{3} = \frac{5}{3}\). Then \(5 \div 3 = 1.666\ldots = 1.\overline{6}\). 3. Divide to convert \(-\frac{13}{11}\): \(-13 \div 11 = -1.181818\ldots = -1.\overline{18}\). 4. Only \(\frac{7}{8}\) has a terminating decimal form.

Answer

\(\frac{7}{8} = 0.875\), terminating \(1\frac{2}{3} = 1.\overline{6}\) \(-\frac{13}{11} = -1.\overline{18}\) Terminating decimal: \(\frac{7}{8}\)
5104057
Convert the fractions to decimals and round them to the nearest thousandth. Then order all four values from least to greatest. \(A = \frac{5}{7}\) \(B = 0.71\) \(C = \frac{11}{15}\) \(D = 0.715\)

Hints

- Convert each fraction by division. - Keep enough decimal places to compare values accurately before rounding. - Align the decimal points when comparing.

Solution

1. Convert \(A\): \(5 \div 7 = 0.714285\ldots\), so \(A \approx 0.714\). 2. Convert \(C\): \(11 \div 15 = 0.7333\ldots\), so \(C \approx 0.733\). 3. Compare the values: \(0.710 < 0.714285\ldots < 0.715 < 0.7333\ldots\). 4. Therefore, \(B < A < D < C\).

Answer

\(0.71 < \frac{5}{7} < 0.715 < \frac{11}{15}\)
5104097
Without performing long division, decide which fractions have terminating decimal forms. Briefly justify each answer using the prime factorization of the denominator after the fraction is simplified. a) \(\frac{7}{25}\) b) \(\frac{9}{12}\) c) \(\frac{13}{40}\) d) \(\frac{11}{30}\)

Hints

- Simplify a fraction before examining its denominator. - A terminating decimal comes from a denominator whose only prime factors are \(2\) and \(5\). - Check whether each fraction is already in simplest form.

Solution

1. A fraction in simplest form has a terminating decimal exactly when its denominator has no prime factors other than \(2\) and \(5\). 2. For a), \(25 = 5^2\), so \(\frac{7}{25}\) has a terminating decimal. 3. For b), \(\frac{9}{12} = \frac{3}{4}\), and \(4 = 2^2\), so the decimal terminates. 4. For c), \(40 = 2^3 \cdot 5\), so \(\frac{13}{40}\) has a terminating decimal. 5. For d), \(30 = 2 \cdot 3 \cdot 5\). The factor \(3\) remains, so the decimal repeats rather than terminates.

Answer

a) Terminating, because \(25 = 5^2\) b) Terminating, because the simplified denominator is \(4 = 2^2\) c) Terminating, because \(40 = 2^3 \cdot 5\) d) Repeating, because the simplified denominator contains a factor of \(3\)
5104107
For the fraction \(\frac{x}{126}\), find the least positive whole number \(x\) that makes the fraction have a terminating decimal form. Explain your reasoning.

Hints

- Find the prime factorization of \(126\). - Identify the prime factors that prevent a terminating decimal. - The numerator must cancel all of those factors. - Look for the smallest product that does so.

Solution

1. Factor the denominator: \(126 = 2 \cdot 3^2 \cdot 7\). 2. After simplification, the denominator may contain only factors of \(2\) and \(5\) for the decimal to terminate. 3. The numerator must cancel the factors \(3^2\) and \(7\). Their product is \(3^2 \cdot 7 = 63\). 4. The least possible value is therefore \(x = 63\). 5. Check: \(\frac{63}{126} = \frac{1}{2} = 0.5\), which terminates.

Answer

\(x = 63\)
5104137
A fraction \(\frac{a}{b}\) in simplest form has a repeating decimal exactly when \(b\) has at least one prime factor other than \(2\) or \(5\). Give three different two-digit numbers that could serve as denominators \(b\) and would always produce a repeating decimal for a fraction in simplest form. Justify each choice.

Hints

- List primes other than \(2\) and \(5\). - Use those primes to form two-digit numbers. - Factor each proposed denominator to justify it.

Solution

1. Each chosen denominator must have at least one prime factor other than \(2\) or \(5\). 2. One choice is \(12\), because \(12 = 2^2 \cdot 3\). The factor \(3\) makes the decimal repeat. 3. A second choice is \(21\), because \(21 = 3 \cdot 7\). Both prime factors produce a repeating decimal. 4. A third choice is \(11\), which is itself a prime other than \(2\) or \(5\). 5. Many other answers are possible, provided the denominator has a prime factor other than \(2\) or \(5\).

Answer

Answers will vary. One possible set is \(11\), \(12\), and \(21\), because each number has a prime factor other than \(2\) or \(5\).
5104217
A recipe calls for \(\frac{3}{8}\) cup of orange juice. Use a number line marked in increments of \(0.1\) cup. a) Convert \(\frac{3}{8}\) to a decimal. b) Describe where the exact amount lies between two consecutive tenth marks. c) Explain why \(\frac{3}{8}\) cup may be more convenient than its decimal form in a US recipe.

Hints

- Divide the numerator by the denominator. - Compare \(0.375\) with the neighboring tenths. - Think about how measuring cups are commonly labeled in US kitchens.

Solution

1. Convert the fraction: \(3 \div 8 = 0.375\), so the amount is \(0.375\) cup. 2. The value lies between \(0.3\) and \(0.4\). Since \(0.375 - 0.3 = 0.075\), it is three-fourths of the way from \(0.3\) to \(0.4\). 3. The fraction \(\frac{3}{8}\) is exact and matches common fractional cup measurements, while \(0.375\) cup is less familiar in everyday recipe directions.

Answer

a) \(0.375\) cup b) It is three-fourths of the way from \(0.3\) to \(0.4\), closer to \(0.4\). c) \(\frac{3}{8}\) cup is exact and aligns with customary fractional cup measurements.
5104227
Three friends share a pizza equally. One student says each person gets exactly \(\frac{1}{3}\) of the pizza. Another says each person gets approximately \(0.33\) of the pizza. a) Add three copies of \(\frac{1}{3}\). b) Add three copies of \(0.33\). c) Explain why the fraction is better when the total must be exact.

Hints

- Add three thirds. - Add the three terminating decimals separately. - Compare an exact fraction with a rounded decimal approximation.

Solution

1. Add the fractions: \(\frac{1}{3} + \frac{1}{3} + \frac{1}{3} = \frac{3}{3} = 1\). 2. Add the decimals: \(0.33 + 0.33 + 0.33 = 0.99\). 3. The fraction \(\frac{1}{3}\) equals the repeating decimal \(0.\overline{3}\). The terminating decimal \(0.33\) is an approximation, so repeated use creates a difference of \(0.01\) from the whole.

Answer

a) \(1\) b) \(0.99\) c) \(\frac{1}{3}\) is exact, while \(0.33\) is a rounded approximation of \(0.\overline{3}\).
5104247
Write each number as a decimal, and then order the original numbers from least to greatest: \(\frac{11}{4}\), \(2.8\), \(2\frac{3}{5}\), \(\frac{27}{10}\)

Hints

- Divide the numerator by the denominator to convert a fraction to a decimal. - Convert the mixed number’s fractional part. - Compare the decimals by aligning place values.

Solution

1. Convert each number: \(\frac{11}{4}=2.75\), \(2.8=2.8\), \(2\frac{3}{5}=2.6\), and \(\frac{27}{10}=2.7\). 2. Compare the decimal forms: \(2.6<2.7<2.75<2.8\). 3. Therefore, \(2\frac{3}{5}<\frac{27}{10}<\frac{11}{4}<2.8\).

Answer

Decimal forms: \(2.75\), \(2.8\), \(2.6\), and \(2.7\) Order: \(2\frac{3}{5}<\frac{27}{10}<\frac{11}{4}<2.8\)
5104257
Which of these numbers lie strictly between \(5.4\) and \(5.7\)? Convert each number to a decimal to check. \(\frac{11}{2}\), \(5\frac{2}{3}\), \(\frac{53}{10}\), \(5.65\) For a repeating decimal, give at least three decimal places or use an exact comparison.

Hints

- Convert each fraction or mixed number to a decimal. - A number must be greater than \(5.4\) and less than \(5.7\). - Keep enough digits of a repeating decimal to make a reliable comparison.

Solution

1. Convert the numbers: \(\frac{11}{2}=5.5\), \(5\frac{2}{3}=5.666\ldots\), \(\frac{53}{10}=5.3\), and \(5.65=5.65\). 2. Check the interval \(5.4<x<5.7\). The values \(5.5\), \(5.666\ldots\), and \(5.65\) satisfy both inequalities. 3. The value \(5.3\) is less than \(5.4\), so it is outside the interval.

Answer

\(\frac{11}{2}\), \(5\frac{2}{3}\), and \(5.65\)
5104337
Convert each fraction or percent to a decimal. \(A = \frac{5}{8}\), \(B = 63\%\), \(C = 0.622\), \(D = \frac{2}{3}\). a) Give each decimal form, rounding \(D\) to the nearest thousandth. b) Order \(A\), \(B\), \(C\), and \(D\) from least to greatest.

Hints

- Convert a fraction by dividing the numerator by the denominator. - Convert a percent by dividing by \(100\). - Compare decimals from left to right by place value.

Solution

1. Convert each value: \(A = \frac{5}{8} = 0.625\), \(B = 63\% = 0.63\), \(C = 0.622\), and \(D = \frac{2}{3} = 0.6666\ldots \approx 0.667\). 2. Compare the exact values: \(0.622 < 0.625 < 0.63 < 0.6666\ldots\). 3. Therefore, \(C < A < B < D\).

Answer

a) \(A = 0.625\); \(B = 0.63\); \(C = 0.622\); \(D \approx 0.667\) b) \(C < A < B < D\)
5104347
Convert each fraction to a decimal and round to the nearest hundredth. Also state the thousandths digit that determines the rounding. a) \(\frac{19}{12}\) b) \(\frac{7}{11}\)

Hints

- Continue the division through at least the thousandths place. - Use the digit immediately to the right of the hundredths place to decide whether to round up.

Solution

1. For a), \(19 \div 12 = 1.5833\ldots\). The thousandths digit is \(3\), so the value rounds to \(1.58\). 2. For b), \(7 \div 11 = 0.636363\ldots\). The thousandths digit is \(6\), so the value rounds to \(0.64\).

Answer

a) \(1.58\); thousandths digit: \(3\) b) \(0.64\); thousandths digit: \(6\)
5104357
Convert each expression to a decimal and round to the nearest hundredth when needed. a) \(112.4\%\) b) \(\frac{5}{13}\) c) \(\frac{25}{6}\)

Hints

- Divide a percent by \(100\) to write it as a decimal. - Convert fractions by division. - Check the thousandths digit when rounding to the nearest hundredth.

Solution

1. For a), \(112.4\% = 1.124\), which rounds to \(1.12\). 2. For b), \(5 \div 13 = 0.384615\ldots\), which rounds to \(0.38\). 3. For c), \(25 \div 6 = 4.1666\ldots\), which rounds to \(4.17\).

Answer

a) \(1.12\) b) \(0.38\) c) \(4.17\)
5104457
Convert the fractions to decimals. Then order all the numbers from least to greatest: \(0.45\), \(\frac{2}{5}\), \(0.405\), \(\frac{1}{2}\), \(\frac{3}{8}\). Show the decimal form you use for each fraction.

Hints

- Rewrite every number in the same form before comparing. - Divide the numerator by the denominator to convert each fraction. - Write zeros at the right of decimals when helpful for comparing place values.

Solution

1. Convert the fractions: \(\frac{2}{5} = 0.4\), \(\frac{1}{2} = 0.5\), and \(\frac{3}{8} = 0.375\). 2. Compare the decimals: \(0.375 < 0.4 < 0.405 < 0.45 < 0.5\). 3. Replace each converted decimal with its original fraction.

Answer

\(\frac{3}{8} < \frac{2}{5} < 0.405 < 0.45 < \frac{1}{2}\)
5104467
Convert the fractions to decimals, then answer both parts for \(1.3\), \(\frac{4}{3}\), \(1.33\), \(1.333\), and \(1\frac{3}{10}\). a) Order the numbers from least to greatest, using \(<\) and \(=\). b) Explain why \(\frac{4}{3}\) and \(1.333\) are not equal.

Hints

- Interpret a fraction bar as division. - Determine whether the decimal form of \(\frac{4}{3}\) terminates or repeats. - Check which numbers are exactly equal before ordering them.

Solution

1. Convert the mixed number: \(1\frac{3}{10} = 1.3\). 2. Convert the improper fraction: \(\frac{4}{3} = 1.3333\ldots = 1.\overline{3}\). 3. Compare the decimal forms: \(1.300 < 1.330 < 1.3330 < 1.3333\ldots\). 4. Therefore, \(1.3 = 1\frac{3}{10} < 1.33 < 1.333 < \frac{4}{3}\). 5. The decimal \(1.333\) stops after three decimal places, while \(\frac{4}{3}\) has infinitely many repeating \(3\)s.

Answer

a) \(1.3 = 1\frac{3}{10} < 1.33 < 1.333 < \frac{4}{3}\) b) \(\frac{4}{3} = 1.\overline{3}\) is a repeating decimal, while \(1.333\) is a terminating decimal, so \(\frac{4}{3} > 1.333\).
5104597
Find the two consecutive hundredths between which \(\frac{5}{6}\) lies. Justify your answer by converting the fraction to a decimal.

Hints

- Divide the numerator by the denominator. - Identify the hundredths immediately below and above the decimal value. - Write trailing zeros when comparing.

Solution

1. Convert the fraction: \(5 \div 6 = 0.8333\ldots = 0.8\overline{3}\). 2. The decimal is greater than \(0.83 = 0.8300\ldots\). 3. It is less than the next hundredth, \(0.84 = 0.8400\ldots\). 4. Therefore, \(0.83 < \frac{5}{6} < 0.84\).

Answer

\(\frac{5}{6}\) lies between \(0.83\) and \(0.84\).
5104647
The fraction \(\frac{3}{n}\) is already in simplest form, and \(10 < n < 30\). Find all values of \(n\) for which the fraction has a terminating decimal form.

Hints

- Because the numerator is \(3\), what must be true about \(n\) if the fraction is in simplest form? - List numbers between \(10\) and \(30\) whose only prime factors are \(2\) and \(5\). - Check powers and products of \(2\) and \(5\) systematically.

Solution

1. Since \(\frac{3}{n}\) is in simplest form, \(n\) is not divisible by \(3\). 2. A terminating decimal requires the denominator to have only prime factors of \(2\) and \(5\). 3. The numbers between \(10\) and \(30\) with only those prime factors are \(16 = 2^4\), \(20 = 2^2 \cdot 5\), and \(25 = 5^2\). 4. None of these values is divisible by \(3\), so all three keep the fraction in simplest form. 5. Therefore, \(n = 16\), \(20\), or \(25\).

Answer

\(n = 16\), \(20\), or \(25\)
5104817
Convert \(\frac{5}{11}\) to a decimal. Then order \(0.45\), \(\frac{5}{11}\), and \(0.454\) from least to greatest.

Hints

- Divide the numerator by the denominator. - Write each decimal to enough places to see the first difference. - Compare the digits from left to right.

Solution

1. Divide to convert the fraction: \(5 \div 11 = 0.\overline{45} = 0.454545\ldots\). 2. Write the terminating decimals with additional zeros: \(0.45 = 0.450000\ldots\) and \(0.454 = 0.454000\ldots\). 3. Comparing digits from left to right gives \(0.450000\ldots < 0.454000\ldots < 0.454545\ldots\).

Answer

\(0.45 < 0.454 < \frac{5}{11}\)
5104837
Which fraction is closest to \(0.41\) on a number line: \(\frac{3}{8}\), \(\frac{2}{5}\), or \(\frac{4}{9}\)? Justify your answer by comparing the distances.

Hints

- Convert each fraction to a decimal. - Find the absolute difference between each decimal and \(0.41\). - Keep enough decimal places to compare the distances accurately.

Solution

1. Convert the fractions to decimals: \(\frac{3}{8}=0.375\), \(\frac{2}{5}=0.4\), and \(\frac{4}{9}=0.444\ldots\). 2. Find the distances from \(0.41\): \(|0.41-0.375|=0.035\) \(|0.41-0.4|=0.01\) \(\left|0.41-0.444\ldots\right|=\frac{31}{900}\approx0.0344\). 3. Since \(0.01\) is the smallest distance, \(\frac{2}{5}\) is closest to \(0.41\).

Answer

\(\frac{2}{5}\)
5104847
Without using long division, simplify each fraction and decide whether its decimal form terminates or repeats. For each terminating decimal, state the number of decimal places. a) \(\frac{42}{105}\) b) \(\frac{33}{120}\) c) \(\frac{9}{72}\)

Hints

- Simplify each fraction first. - A terminating decimal has only factors of \(2\) and \(5\) in its simplified denominator. - The larger exponent of \(2\) and \(5\) determines the number of decimal places.

Solution

1. For a), \(\frac{42}{105} = \frac{2}{5}\). The denominator is \(5^1\), so the decimal terminates with \(1\) decimal place. 2. For b), \(\frac{33}{120} = \frac{11}{40}\), and \(40 = 2^3 \cdot 5\). The decimal terminates with \(\max(3, 1) = 3\) decimal places. 3. For c), \(\frac{9}{72} = \frac{1}{8}\), and \(8 = 2^3\). The decimal terminates with \(3\) decimal places.

Answer

a) Terminating; \(1\) decimal place b) Terminating; \(3\) decimal places c) Terminating; \(3\) decimal places
5104857
Analyze the decimal form of each fraction. Identify the fraction with a repeating decimal, and state the number of decimal places for each terminating decimal. a) \(\frac{13}{65}\) b) \(\frac{14}{350}\) c) \(\frac{7}{30}\)

Hints

- Simplify each fraction before examining its denominator. - A prime factor other than \(2\) or \(5\) causes repetition. - Distinguish total decimal places from nonrepeating digits before a repeating block.

Solution

1. For a), \(\frac{13}{65} = \frac{1}{5}\). The simplified denominator has only the prime factor \(5\), so the decimal terminates with \(1\) decimal place. 2. For b), \(\frac{14}{350} = \frac{1}{25} = \frac{1}{5^2}\). The decimal terminates with \(2\) decimal places. 3. For c), \(\frac{7}{30}\) is in simplest form, and \(30 = 2 \cdot 3 \cdot 5\). The factor \(3\) makes the decimal repeat. In fact, \(\frac{7}{30} = 0.2\overline{3}\), with one nonrepeating digit before the repeating part.

Answer

a) Terminating; \(1\) decimal place b) Terminating; \(2\) decimal places c) Repeating; \(0.2\overline{3}\) has one nonrepeating decimal digit
5104867
You can predict the number of decimal places in a terminating decimal without carrying out the division. a) Determine the number of decimal places in \(\frac{27}{1200}\). b) Compare it with \(\frac{19}{400}\). What do you notice? Justify your answer using prime factorizations of the denominators.

Hints

- Simplify each fraction first. - Factor the simplified denominator into powers of \(2\) and \(5\). - The larger exponent tells how many decimal places are needed.

Solution

1. Simplify the first fraction: \(\frac{27}{1200} = \frac{9}{400}\). 2. Factor the denominator: \(400 = 2^4 \cdot 5^2\). 3. The greater exponent is \(4\), so \(\frac{27}{1200}\) has a terminating decimal with \(4\) decimal places. 4. The fraction \(\frac{19}{400}\) is already in simplest form and has the same denominator, so it also has \(4\) decimal places. 5. Indeed, \(\frac{9}{400} = 0.0225\) and \(\frac{19}{400} = 0.0475\).

Answer

a) \(4\) decimal places b) Both fractions have \(4\) decimal places because, after simplifying, both denominators are \(400 = 2^4 \cdot 5^2\).
5104917
Convert \(2\frac{5}{11}\) to a decimal. Which digit is in the \(50\)th place after the decimal point? Explain using the repeating pattern.

Hints

- Convert only the fractional part first. - Identify the length of the repeating block. - Decide whether the target position is odd or even.

Solution

1. Convert the fractional part: \(5 \div 11 = 0.454545\ldots = 0.\overline{45}\). 2. Therefore, \(2\frac{5}{11} = 2.\overline{45}\). 3. The repeating block has length \(2\): \(4\) occurs in odd-numbered decimal places and \(5\) occurs in even-numbered decimal places. 4. Since \(50\) is even, the \(50\)th digit is \(5\).

Answer

\(2\frac{5}{11} = 2.\overline{45}\). The \(50\)th digit after the decimal point is \(5\).
5104927
Convert \(\frac{5}{12}\) and \(-\frac{7}{11}\) to decimals. For each result, state the period length, meaning the number of digits in the repeating block. Which fraction has the longer period?

Hints

- The negative sign does not change the repeating digit pattern. - Separate any nonrepeating digits from the repeating block. - Count only the digits in the repeating block.

Solution

1. Convert \(\frac{5}{12}\): \(5 \div 12 = 0.41666\ldots = 0.41\overline{6}\). Its repeating block is \(6\), so the period length is \(1\). 2. Convert \(-\frac{7}{11}\): \(-7 \div 11 = -0.636363\ldots = -0.\overline{63}\). Its repeating block is \(63\), so the period length is \(2\). 3. Therefore, \(-\frac{7}{11}\) has the longer period.

Answer

\(\frac{5}{12} = 0.41\overline{6}\), period length \(1\) \(-\frac{7}{11} = -0.\overline{63}\), period length \(2\) \(-\frac{7}{11}\) has the longer period.
5104937
Round each number to the nearest tenth and nearest hundredth. a) \(0.\overline{5}\) b) \(1.274\) c) \(-0.\overline{18}\) d) \(3.009\)

Hints

- Write several digits of each repeating decimal. - Look at the digit immediately to the right of the requested place. - Preserve trailing zeros that show the requested rounding place.

Solution

1. For a), \(0.\overline{5}=0.555\ldots\). It rounds to \(0.6\) to the nearest tenth and \(0.56\) to the nearest hundredth. 2. For b), \(1.274\) rounds to \(1.3\) to the nearest tenth and \(1.27\) to the nearest hundredth. 3. For c), \(-0.\overline{18}=-0.1818\ldots\). It rounds to \(-0.2\) to the nearest tenth and \(-0.18\) to the nearest hundredth. 4. For d), \(3.009\) rounds to \(3.0\) to the nearest tenth and \(3.01\) to the nearest hundredth.

Answer

a) Tenth: \(0.6\); hundredth: \(0.56\) b) Tenth: \(1.3\); hundredth: \(1.27\) c) Tenth: \(-0.2\); hundredth: \(-0.18\) d) Tenth: \(3.0\); hundredth: \(3.01\)
5104947
Let \(A=0.\overline{27}\) and \(B=0.27\). When rounded to the nearest tenth, hundredth, and thousandth, at which place do the rounded values first differ?

Hints

- Write both numbers with at least four decimal places. - Round each number to each requested place in order. - Add trailing zeros to the terminating decimal when needed to show the same precision.

Solution

1. Write the decimals as \(A=0.272727\ldots\) and \(B=0.270000\ldots\). 2. To the nearest tenth, both numbers round to \(0.3\). 3. To the nearest hundredth, both numbers round to \(0.27\). 4. To the nearest thousandth, \(A\) rounds to \(0.273\), while \(B\) is written as \(0.270\). 5. Therefore, the rounded values first differ at the thousandths place.

Answer

They first differ when rounded to the nearest thousandth: \(0.273\) and \(0.270\).
5104997
Convert each fraction to a decimal. Classify each result as terminating, repeating with no nonrepeating digits, or repeating with a nonrepeating beginning. a) \(\frac{7}{9}\) b) \(\frac{13}{40}\) c) \(\frac{5}{6}\)

Hints

- Divide each numerator by its denominator. - A remainder of zero produces a terminating decimal. - If a remainder repeats, identify where the repeating block begins.

Solution

1. For a), \(7 \div 9 = 0.777\ldots = 0.\overline{7}\). The repeating block begins immediately. 2. For b), \(13 \div 40 = 0.325\). The division ends, so the decimal terminates. 3. For c), \(5 \div 6 = 0.8333\ldots = 0.8\overline{3}\). The digit \(8\) comes before the repeating block.

Answer

a) \(0.\overline{7}\), repeating with no nonrepeating digits b) \(0.325\), terminating c) \(0.8\overline{3}\), repeating with a nonrepeating beginning
5105027
Convert fractions to decimals as needed. Insert \(<\), \(>\), or \(=\) in each statement. a) \(0.81 \;\square\; \frac{9}{11}\) b) \(0.\overline{12} \;\square\; 0.121\) c) \(2.66 \;\square\; 2.\overline{6}\) d) \(\frac{3}{8} \;\square\; 0.375\)

Hints

- Expand repeating decimals by several digits. - Convert fractions by dividing the numerator by the denominator. - Add trailing zeros when comparing terminating decimals.

Solution

1. For a), \(\frac{9}{11} = 0.818181\ldots\), so \(0.81 < \frac{9}{11}\). 2. For b), \(0.\overline{12} = 0.121212\ldots\), which is greater than \(0.121000\ldots\). 3. For c), \(2.\overline{6} = 2.6666\ldots\), which is greater than \(2.6600\ldots\). 4. For d), \(\frac{3}{8} = 0.375\), so the values are equal.

Answer

a) \(0.81 < \frac{9}{11}\) b) \(0.\overline{12} > 0.121\) c) \(2.66 < 2.\overline{6}\) d) \(\frac{3}{8} = 0.375\)
5105057
Convert the fraction to a decimal. Then order the numbers from greatest to least: \(0.6\), \(\frac{2}{3}\), \(0.\overline{6}\), \(0.666\).

Hints

- Convert \(\frac{2}{3}\) by division. - Recall what a bar over a decimal digit means. - Compare enough decimal places to find the first difference.

Solution

1. Convert the fraction: \(\frac{2}{3} = 0.6666\ldots = 0.\overline{6}\). 2. Write the terminating decimals with additional zeros: \(0.6 = 0.6000\ldots\) and \(0.666 = 0.6660\ldots\). 3. The two repeating decimals are equal and are greater than \(0.666\), which is greater than \(0.6\).

Answer

\(\frac{2}{3} = 0.\overline{6} > 0.666 > 0.6\)
5105067
Write each number as a decimal, then order the numbers from least to greatest: \(-0.75\), \(-0.7\overline{5}\), \(-0.\overline{75}\), \(-\frac{3}{4}\).

Hints

- Expand each repeating decimal by several digits. - Convert the fraction to a decimal. - Remember how order reverses when comparing negative values by absolute value.

Solution

1. Convert the fraction: \(-\frac{3}{4} = -0.75\). 2. Expand the repeating decimals: \(-0.7\overline{5} = -0.75555\ldots\) and \(-0.\overline{75} = -0.757575\ldots\). 3. For negative numbers, the number with the greater absolute value is less. 4. Therefore, \(-0.757575\ldots < -0.75555\ldots < -0.75\).

Answer

\(-0.\overline{75} < -0.7\overline{5} < -0.75 = -\frac{3}{4}\)
5105077
Convert any fractions to decimals as needed. Insert \(<\), \(>\), or \(=\) to make each statement true. a) \(0.45 \;\square\; \frac{5}{11}\) b) \(-0.62 \;\square\; -\frac{5}{8}\) c) \(0.\overline{9} \;\square\; 1\) d) \(1.2\overline{3} \;\square\; 1.\overline{23}\)

Hints

- Convert the fractions to decimals before comparing. - Be careful with the order of negative numbers. - Recall the value of \(0.\overline{9}\). - Expand both repeating decimals in d) until you see the first different digit.

Solution

1. For a), \(\frac{5}{11} = 0.4545\ldots\), so \(0.45 < \frac{5}{11}\). 2. For b), \(-\frac{5}{8} = -0.625\). Since \(-0.620 > -0.625\), \(-0.62 > -\frac{5}{8}\). 3. For c), \(0.\overline{9} = 1\). 4. For d), \(1.2\overline{3} = 1.2333\ldots\) and \(1.\overline{23} = 1.2323\ldots\). At the third decimal place, \(3 > 2\), so \(1.2\overline{3} > 1.\overline{23}\).

Answer

a) \(<\) b) \(>\) c) \(=\) d) \(>\)
5105087
Explain the error in each statement and correct it. a) \(\frac{4}{9} = 0.4\) b) \(0.\overline{7} = \frac{7}{10}\) c) \(\frac{1}{11} = 0.09\)

Hints

- Divide the numerator by the denominator to check each claim. - Distinguish terminating decimals from repeating decimals. - For a one-digit repeating block that begins immediately, consider a denominator of \(9\).

Solution

1. For a), \(4 \div 9 = 0.444\ldots\), so the repeating bar is missing. The correct statement is \(\frac{4}{9} = 0.\overline{4}\). 2. For b), \(0.\overline{7}\) is repeating, not terminating. The correct fraction is \(\frac{7}{9}\). 3. For c), \(1 \div 11 = 0.090909\ldots\), so the correct decimal is \(0.\overline{09}\).

Answer

a) The repeating bar is missing: \(\frac{4}{9} = 0.\overline{4}\). b) A repeating decimal was treated as a terminating decimal: \(0.\overline{7} = \frac{7}{9}\). c) The repeating pattern was omitted: \(\frac{1}{11} = 0.\overline{09}\).
5105097
Check each claim, identify the error, and correct the result. a) \(\frac{2}{3}\), rounded to the nearest hundredth, is \(0.66\). b) \(0.4\overline{5} = 0.4545\ldots\) c) \(\frac{1}{3} = 0.3\), so \(\frac{2}{3} = 0.6\). d) \(\frac{8}{99} = 0.88\)

Hints

- Check the digit immediately to the right of the rounding place. - Look carefully at which digits are covered by the repeating bar. - Decide whether each fraction can have a terminating decimal form.

Solution

1. For a), \(\frac{2}{3} = 0.666\ldots\). The thousandths digit is \(6\), so the value rounds to \(0.67\). 2. For b), the bar is only over the digit \(5\), so \(0.4\overline{5} = 0.4555\ldots\). 3. For c), \(\frac{1}{3} = 0.\overline{3}\), not \(0.3\). Therefore, \(\frac{2}{3} = 0.\overline{6}\). 4. For d), \(8 \div 99 = 0.080808\ldots = 0.\overline{08}\).

Answer

a) The value was rounded down incorrectly: \(\frac{2}{3} \approx 0.67\). b) The repeating block was misread: \(0.4\overline{5} = 0.4555\ldots\). c) The repeating bar was omitted: \(\frac{2}{3} = 0.\overline{6}\). d) Repetition was ignored: \(\frac{8}{99} = 0.\overline{08}\).
5105127
A proper fraction has the form \(\frac{n}{140}\), where \(1 \le n < 140\). Find every positive whole number \(n\) for which the fraction has a terminating decimal form. How many such fractions are there?

Hints

- Factor \(140\). - Identify the prime factor that must disappear from the denominator. - Determine what divisibility condition this places on \(n\). - Count the multiples in the allowed range.

Solution

1. Factor the denominator: \(140 = 2^2 \cdot 5 \cdot 7\). 2. After simplification, a terminating decimal may have only prime factors of \(2\) and \(5\) in the denominator. 3. Therefore, the factor \(7\) must cancel, so \(n\) must be a multiple of \(7\). 4. The multiples of \(7\) from \(1\) through \(139\) are \(7, 14, 21, \ldots, 133\). 5. Since \(133 \div 7 = 19\), there are \(19\) possible values of \(n\).

Answer

\(n \in \{7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105, 112, 119, 126, 133\}\). There are \(19\) such fractions.
5105147
Convert each fraction to a repeating decimal: \(\frac{2}{9}\), \(\frac{7}{33}\), and \(\frac{25}{99}\). Then order the values from least to greatest.

Hints

- Try rewriting each fraction with a denominator made of nines. - You can also divide each numerator by its denominator. - Compare the decimal digits from left to right.

Solution

1. Divide \(2\) by \(9\): \(\frac{2}{9} = 0.222\ldots = 0.\overline{2}\). 2. Rewrite \(\frac{7}{33}\) with a denominator of \(99\): \(\frac{7}{33} = \frac{21}{99} = 0.\overline{21}\). 3. A numerator over \(99\) gives the two-digit repeating block directly: \(\frac{25}{99} = 0.\overline{25}\). 4. Compare the decimal forms: \(0.2121\ldots < 0.2222\ldots < 0.2525\ldots\). 5. Therefore, \(\frac{7}{33} < \frac{2}{9} < \frac{25}{99}\).

Answer

\(\frac{2}{9} = 0.\overline{2}\), \(\frac{7}{33} = 0.\overline{21}\), and \(\frac{25}{99} = 0.\overline{25}\). Least to greatest: \(\frac{7}{33} < \frac{2}{9} < \frac{25}{99}\).
5105177
Explore the fractions \(\frac{1}{9}\), \(\frac{2}{9}\), and \(\frac{3}{9}\). a) Convert them to decimals. What pattern do you notice? b) Use the pattern to write the decimal forms of \(\frac{7}{9}\) and \(\frac{8}{9}\) without long division. c) Predict the decimal forms of \(\frac{1}{99}\) and \(\frac{12}{99}\). Check your predictions.

Hints

- Calculate the first few divisions and compare each numerator with its repeating block. - Compare the number of nines in the denominator with the number of digits in the repeating block. - Remember to include a leading zero in a two-digit block when needed.

Solution

1. The first decimals are \(\frac{1}{9} = 0.\overline{1}\), \(\frac{2}{9} = 0.\overline{2}\), and \(\frac{3}{9} = 0.\overline{3}\). 2. The numerator becomes the one-digit repeating block. 3. Therefore, \(\frac{7}{9} = 0.\overline{7}\) and \(\frac{8}{9} = 0.\overline{8}\). 4. With denominator \(99\), the repeating block has two digits. Thus, \(\frac{1}{99} = 0.\overline{01}\) and \(\frac{12}{99} = 0.\overline{12}\). 5. Long division confirms both predictions.

Answer

a) \(\frac{1}{9} = 0.\overline{1}\), \(\frac{2}{9} = 0.\overline{2}\), and \(\frac{3}{9} = 0.\overline{3}\). The numerator becomes the repeating digit. b) \(\frac{7}{9} = 0.\overline{7}\); \(\frac{8}{9} = 0.\overline{8}\) c) \(\frac{1}{99} = 0.\overline{01}\); \(\frac{12}{99} = 0.\overline{12}\)
5105197
Compare the decimal forms of \(\frac{1}{13}\) and \(\frac{3}{13}\). a) Find both repeating decimals. What do you notice about their repeating blocks? b) Now find \(\frac{2}{13}\). Does it belong to the same “family,” meaning that it uses the same digits in a cyclic shift? Explain using the remainders from long division.

Hints

- Record every remainder during the division of \(1\) by \(13\). - Compare that remainder list with the numerators of the other fractions. - If a numerator appears as a remainder, the same digit cycle restarts from that point.

Solution

1. Long division gives \(\frac{1}{13} = 0.\overline{076923}\). Its successive nonzero remainders are \(10, 9, 12, 3, 4, 1\). 2. Also, \(\frac{3}{13} = 0.\overline{230769}\). Its repeating block is a cyclic shift of \(076923\). 3. This happens because the remainder \(3\) occurs in the remainder cycle for \(1 \div 13\). Starting with \(3\) continues the same cycle from that point. 4. Long division gives \(\frac{2}{13} = 0.\overline{153846}\). 5. The remainder \(2\) does not appear in the remainder cycle for \(\frac{1}{13}\), so \(\frac{2}{13}\) begins a different cycle and does not use a cyclic shift of the same repeating block.

Answer

a) \(\frac{1}{13} = 0.\overline{076923}\) and \(\frac{3}{13} = 0.\overline{230769}\). Their repeating blocks are cyclic shifts. b) \(\frac{2}{13} = 0.\overline{153846}\). It is not in the same family because the starting remainder \(2\) does not occur in the remainder cycle for \(1 \div 13\).
5105227
Explore fractions with denominator \(11\), such as \(\frac{1}{11}, \frac{2}{11}, \ldots, \frac{10}{11}\). a) Convert the first three fractions to decimals. What pattern connects each numerator to the repeating block? b) Use the pattern to write the decimal forms of \(\frac{7}{11}\) and \(\frac{9}{11}\). c) Is there a similar pattern for denominator \(9\)? Check \(\frac{1}{9}\) and \(\frac{2}{9}\).

Hints

- Compare each repeating block with a multiple of \(9\). - Multiply the numerator by \(9\) to predict the two-digit block. - Check whether denominator \(9\) produces a one-digit or two-digit repeating block.

Solution

1. The first three values are \(\frac{1}{11} = 0.\overline{09}\), \(\frac{2}{11} = 0.\overline{18}\), and \(\frac{3}{11} = 0.\overline{27}\). 2. Each two-digit repeating block is \(9\) times the numerator. 3. Since \(7 \cdot 9 = 63\), \(\frac{7}{11} = 0.\overline{63}\). Since \(9 \cdot 9 = 81\), \(\frac{9}{11} = 0.\overline{81}\). 4. For denominator \(9\), \(\frac{1}{9} = 0.\overline{1}\) and \(\frac{2}{9} = 0.\overline{2}\). The one-digit repeating block equals the numerator.

Answer

a) \(\frac{1}{11} = 0.\overline{09}\), \(\frac{2}{11} = 0.\overline{18}\), and \(\frac{3}{11} = 0.\overline{27}\). The repeating block is \(9\) times the numerator. b) \(\frac{7}{11} = 0.\overline{63}\); \(\frac{9}{11} = 0.\overline{81}\) c) Yes. For denominator \(9\), the repeating digit equals the numerator.
5105237
Convert the fractions to decimals, then order the numbers from least to greatest: \(\frac{7}{20}\), \(0.36\), \(\frac{1}{3}\), \(0.3\overline{5}\), \(0.34\).

Hints

- Convert each fraction by dividing the numerator by the denominator. - Expand repeating decimals by several digits. - Compare the digits from left to right.

Solution

1. Convert the fractions: \(\frac{7}{20} = 0.35\) and \(\frac{1}{3} = 0.3333\ldots = 0.\overline{3}\). 2. Expand the other repeating decimal: \(0.3\overline{5} = 0.3555\ldots\). 3. Compare the decimals: \(0.3333\ldots < 0.34 < 0.35 < 0.3555\ldots < 0.36\).

Answer

\(\frac{1}{3} < 0.34 < \frac{7}{20} < 0.3\overline{5} < 0.36\)
5105247
Convert the fraction to a decimal, then order the numbers from least to greatest: \(a = -1.25\), \(b = -\frac{5}{4}\), \(c = -1.2\overline{5}\), and \(d = -1.2\).

Hints

- Convert the fraction to a decimal. - Expand the repeating decimal by several digits. - Remember that more negative numbers lie farther left on the number line.

Solution

1. Convert the fraction: \(b = -\frac{5}{4} = -1.25\). 2. Expand the repeating decimal: \(c = -1.2555\ldots\). 3. Write \(d = -1.20\) to compare place values. 4. For negative numbers, the value with the greater absolute value is less. Thus, \(-1.2555\ldots < -1.25 < -1.20\).

Answer

\(-1.2\overline{5} < -1.25 = -\frac{5}{4} < -1.2\)
5105277
A fraction has the form \(\frac{k}{60}\). Find every positive whole number \(k\) with \(1 \le k < 60\) for which the fraction has a terminating decimal form. Justify your answer using the prime factorization of the denominator.

Hints

- Factor \(60\). - Identify the prime factor that prevents termination. - Determine what must be true of \(k\) for that factor to cancel. - List all matching values in the given range.

Solution

1. Factor the denominator: \(60 = 2^2 \cdot 3 \cdot 5\). 2. A fraction in simplest form has a terminating decimal only when its denominator has no prime factors other than \(2\) and \(5\). 3. Therefore, the factor \(3\) must cancel, so \(k\) must be divisible by \(3\). 4. The possible values are \(3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57\).

Answer

\(k \in \{3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57\}\)
5105477
Insert \(<\), \(>\), or \(=\) to make each statement true. a) \(0.\overline{7} \;\square\; 0.77\) b) \(-1.23 \;\square\; -1.229\) c) \(0.05 \;\square\; \frac{1}{20}\) d) \(-0.001 \;\square\; -0.01\)

Hints

- Expand a repeating decimal by several digits. - Write terminating decimals with the same number of places when helpful. - Convert the fraction to a decimal. - For negative values, consider which number lies farther right on the number line.

Solution

1. For a), \(0.\overline{7} = 0.777\ldots\), so \(0.\overline{7} > 0.77\). 2. For b), write \(-1.23 = -1.230\). Since \(-1.230 < -1.229\), \(-1.23 < -1.229\). 3. For c), \(\frac{1}{20} = \frac{5}{100} = 0.05\), so the values are equal. 4. For d), \(-0.001\) is closer to zero than \(-0.01\), so \(-0.001 > -0.01\).

Answer

a) \(0.\overline{7} > 0.77\) b) \(-1.23 < -1.229\) c) \(0.05 = \frac{1}{20}\) d) \(-0.001 > -0.01\)
5105487
Convert fractions to decimals as needed. Insert \(<\), \(>\), or \(=\) in each statement. a) \(-\frac{5}{4} \;\square\; -1.2\) b) \(0.\overline{15} \;\square\; 0.151\) c) \(-3.45 \;\square\; -3.455\) d) \(2.08 \;\square\; 2\frac{2}{25}\)

Hints

- Convert fractions or mixed numbers to decimals first. - Expand repeating decimals by several digits. - For negative values, the number with greater absolute value is less.

Solution

1. For a), \(-\frac{5}{4} = -1.25\), and \(-1.25 < -1.2\). 2. For b), \(0.\overline{15} = 0.151515\ldots\), which is greater than \(0.151000\ldots\). 3. For c), \(-3.45 = -3.450\), which is greater than \(-3.455\). 4. For d), \(2\frac{2}{25} = 2 + \frac{8}{100} = 2.08\), so the values are equal.

Answer

a) \(-\frac{5}{4} < -1.2\) b) \(0.\overline{15} > 0.151\) c) \(-3.45 > -3.455\) d) \(2.08 = 2\frac{2}{25}\)
5105497
Convert the fraction to a decimal, then order the numbers from least to greatest using \(<\) and \(=\): \(-0.3\), \(-\frac{1}{3}\), \(-0.33\), \(-0.\overline{3}\), \(-0.34\).

Hints

- Convert every number to decimal form. - Align the decimal points and add trailing zeros when helpful. - Check whether any two values are equal.

Solution

1. Convert the fraction: \(-\frac{1}{3} = -0.3333\ldots = -0.\overline{3}\). 2. Write the terminating decimals with additional zeros: \(-0.3 = -0.3000\ldots\), \(-0.33 = -0.3300\ldots\), and \(-0.34 = -0.3400\ldots\). 3. For negative numbers, the value with the greater absolute value is less. 4. Therefore, \(-0.34 < -0.\overline{3} = -\frac{1}{3} < -0.33 < -0.3\).

Answer

\(-0.34 < -0.\overline{3} = -\frac{1}{3} < -0.33 < -0.3\)
5105687
Convert each fraction to a decimal. Use a bar to mark the repeating digits. a) \(\frac{4}{9}\) b) \(\frac{4}{99}\) c) \(\frac{4}{90}\) d) \(\frac{41}{99}\)

Hints

- A denominator of \(9\) or \(99\) often reveals the repeating block directly. - Dividing by \(10\) shifts every decimal digit one place to the right. - Compare the number of nines in the denominator with the length of the repeating block.

Solution

1. For a), \(4 \div 9 = 0.444\ldots = 0.\overline{4}\). 2. For b), \(4 \div 99 = 0.040404\ldots = 0.\overline{04}\). 3. For c), \(\frac{4}{90} = \frac{4}{9} \div 10\). Dividing by \(10\) shifts the digits one place to the right, so the result is \(0.0\overline{4}\). 4. For d), \(41 \div 99 = 0.414141\ldots = 0.\overline{41}\).

Answer

a) \(0.\overline{4}\) b) \(0.\overline{04}\) c) \(0.0\overline{4}\) d) \(0.\overline{41}\)
5105697
Analyze the decimal form of \(\frac{1}{11}\). a) Find the decimal form of \(\frac{1}{11}\) using long division. b) Use that result to find \(\frac{3}{11}\) without repeating the long division. c) What is the decimal form of \(\frac{1}{110}\)? Briefly explain its connection to part a).

Hints

- Track the remainders in \(1 \div 11\). - Multiply the decimal from part a) by \(3\). - Think about what dividing a decimal by \(10\) does to its digits.

Solution

1. Long division gives \(1 \div 11 = 0.0909\ldots = 0.\overline{09}\). 2. Multiply the result by \(3\): \(3 \cdot 0.\overline{09} = 0.\overline{27}\). Thus, \(\frac{3}{11} = 0.\overline{27}\). 3. Since \(\frac{1}{110} = \frac{1}{11} \div 10\), every digit shifts one place to the right. Therefore, \(\frac{1}{110} = 0.0\overline{09}\).

Answer

a) \(0.\overline{09}\) b) \(0.\overline{27}\) c) \(0.0\overline{09}\), because dividing by \(10\) shifts the digits one place to the right.
5105747
Convert each fraction or percent to a decimal. Then order the numbers from least to greatest: \(0.72\), \(\frac{3}{4}\), \(70\%\), \(\frac{13}{20}\).

Hints

- Convert all values to the same form. - Write each percent as a decimal by dividing by \(100\). - Convert fractions using division or an equivalent fraction with denominator \(100\).

Solution

1. Convert the fraction and percent forms: \(\frac{3}{4} = 0.75\), \(70\% = 0.70\), and \(\frac{13}{20} = \frac{65}{100} = 0.65\). 2. Compare the decimals: \(0.65 < 0.70 < 0.72 < 0.75\). 3. Replace the converted values with their original forms.

Answer

\(\frac{13}{20} < 70\% < 0.72 < \frac{3}{4}\)
5105767
Three of these numbers have the same value, and one does not belong. Identify the number that does not belong, and justify your choice by converting all four numbers to the same form: \(0.375\), \(\frac{3}{8}\), \(37.5\%\), \(\frac{375}{100}\)

Hints

- Convert all four numbers to decimals. - To convert a percent to a decimal, divide by \(100\). - Notice that \(0.375 = \frac{375}{1000}\), not \(\frac{375}{100}\).

Solution

1. Convert each value to a decimal. The first value is already \(0.375\). 2. Divide to convert the fraction: \(\frac{3}{8} = 3 \div 8 = 0.375\). 3. Divide the percent by \(100\): \(37.5\% = 0.375\). 4. Convert the last fraction: \(\frac{375}{100} = 3.75\). 5. The first three values are equal. The value \(3.75\) is ten times \(0.375\), so \(\frac{375}{100}\) does not belong.

Answer

\(\frac{375}{100}\) does not belong because it equals \(3.75\), while each of the other three values equals \(0.375\).
5105837
Write each fraction in simplest form. Then convert it to a decimal. a) \(\frac{45}{60}\) b) \(\frac{26}{65}\) c) \(\frac{132}{48}\) d) \(\frac{51}{85}\)

Hints

- Look for a common factor of the numerator and denominator. - Remember to consider prime factors such as \(13\) and \(17\). - After simplifying, divide the numerator by the denominator.

Solution

1. For a), divide the numerator and denominator by \(15\): \(\frac{45}{60} = \frac{3}{4}\). Then \(3 \div 4 = 0.75\). 2. For b), divide the numerator and denominator by \(13\): \(\frac{26}{65} = \frac{2}{5}\). Then \(2 \div 5 = 0.4\). 3. For c), divide the numerator and denominator by \(12\): \(\frac{132}{48} = \frac{11}{4}\). Then \(11 \div 4 = 2.75\). 4. For d), divide the numerator and denominator by \(17\): \(\frac{51}{85} = \frac{3}{5}\). Then \(3 \div 5 = 0.6\).

Answer

a) \(\frac{3}{4} = 0.75\) b) \(\frac{2}{5} = 0.4\) c) \(\frac{11}{4} = 2.75\) d) \(\frac{3}{5} = 0.6\)
5105847
Compare \(\frac{18}{24}\) and \(\frac{14}{20}\). Write each fraction in simplest form and convert it to a decimal. Which fraction is greater?

Hints

- Simplify each fraction by dividing the numerator and denominator by a common factor. - Convert each simplified fraction to a decimal. - Compare the decimals digit by digit.

Solution

1. The greatest common factor of \(18\) and \(24\) is \(6\): \(\frac{18}{24} = \frac{18 \div 6}{24 \div 6} = \frac{3}{4}\). 2. Convert the simplified fraction: \(3 \div 4 = 0.75\). 3. The greatest common factor of \(14\) and \(20\) is \(2\): \(\frac{14}{20} = \frac{14 \div 2}{20 \div 2} = \frac{7}{10}\). 4. Convert the simplified fraction: \(7 \div 10 = 0.7\). 5. Since \(0.75 > 0.7\), \(\frac{18}{24} > \frac{14}{20}\).

Answer

\(\frac{18}{24} = \frac{3}{4} = 0.75\) and \(\frac{14}{20} = \frac{7}{10} = 0.7\). Therefore, \(\frac{18}{24}\) is greater.
5105917
Two students discuss \(\frac{18}{75}\). Student A says, “The decimal repeats because the denominator \(75\) is divisible by \(3\).” Student B replies, “That conclusion cannot be made until the fraction is in simplest form.” Who is correct? Decide whether the decimal terminates or repeats, and justify your answer with a calculation.

Hints

- Simplify the fraction before analyzing its denominator. - Identify the prime factors that remain in the simplified denominator. - A terminating decimal has only factors of \(2\) and \(5\) in its denominator.

Solution

1. Student B is correct because the denominator must be examined after the fraction is simplified. 2. Simplify: \(\frac{18}{75} = \frac{6}{25}\). 3. The simplified denominator is \(25 = 5^2\), which has no prime factors other than \(5\). 4. Therefore, the decimal terminates. In fact, \(\frac{6}{25} = 0.24\).

Answer

Student B is correct. \(\frac{18}{75} = \frac{6}{25} = 0.24\), so the decimal terminates because the simplified denominator is \(25 = 5^2\).
5105927
Convert fractions and percents to decimals. Then order the numbers from least to greatest using \(<\) and \(=\): \(-\frac{3}{4}\), \(0.7\), \(-0.8\), \(75\%\), \(\frac{2}{3}\), \(-0.75\).

Hints

- Convert every value to decimal form. - Compare the negative values separately from the positive values. - Check whether any two forms represent the same number.

Solution

1. Convert the nondecimal forms: \(-\frac{3}{4} = -0.75\), \(75\% = 0.75\), and \(\frac{2}{3} = 0.6666\ldots\). 2. Order the negative values: \(-0.8 < -0.75\), and \(-\frac{3}{4} = -0.75\). 3. Order the positive values: \(0.6666\ldots < 0.7 < 0.75\). 4. Combine the two groups.

Answer

\(-0.8 < -\frac{3}{4} = -0.75 < \frac{2}{3} < 0.7 < 75\%\)
5106017
Convert the fractions to decimals, then order the numbers from least to greatest using \(<\) and \(=\): \(-\frac{2}{5}\), \(0.35\), \(-0.45\), \(\frac{1}{4}\), \(-0.4\), \(0\).

Hints

- Separate negative, zero, and positive values. - Convert each fraction to a decimal. - Check whether any decimal and fraction are equal.

Solution

1. Convert the fractions: \(-\frac{2}{5} = -0.4\) and \(\frac{1}{4} = 0.25\). 2. Order the negative values: \(-0.45 < -0.4 = -\frac{2}{5}\). 3. Place zero between the negative and positive values. 4. Order the positive values: \(0.25 < 0.35\).

Answer

\(-0.45 < -0.4 = -\frac{2}{5} < 0 < \frac{1}{4} < 0.35\)
5106627
Evaluate each expression. Decide whether fractions, decimals, or a combination of both is most efficient. a) \(\left(\frac{1}{4} + 0.5\right) - 1\) b) \(2.75 - \left(1\frac{1}{2} + 0.25\right)\) c) \(\frac{1}{3} + 0.2 + \frac{1}{6}\)

Hints

- Examine the whole expression before choosing a representation. - Avoid converting a fraction to a repeating decimal when fraction addition is simpler. - Look for values that combine to a whole number or a simple decimal.

Solution

1. For a), use \(\frac{1}{4} = 0.25\): \((0.25 + 0.5) - 1 = 0.75 - 1 = -0.25\). 2. For b), use \(1\frac{1}{2} = 1.5\): \(2.75 - (1.5 + 0.25) = 2.75 - 1.75 = 1\). 3. For c), add the fractions first: \(\frac{1}{3} + \frac{1}{6} = \frac{1}{2} = 0.5\). Then \(0.5 + 0.2 = 0.7\).

Answer

a) \(-0.25\) b) \(1\) c) \(0.7\)
5106897
Evaluate the expression. Briefly explain why fractions or decimals are the better representation. \(1\frac{1}{3} + 0.25 - \frac{7}{12}\)

Hints

- Consider the decimal representation of \(\frac{1}{3}\). - Convert the terminating decimal to a fraction. - Rewrite the fractions with a common denominator.

Solution

1. Fractions are more efficient because \(\frac{1}{3}\) has a repeating decimal representation. 2. Convert \(0.25 = \frac{1}{4}\) and \(1\frac{1}{3} = \frac{4}{3}\). 3. Use denominator \(12\): \(\frac{16}{12} + \frac{3}{12} - \frac{7}{12} = \frac{12}{12} = 1\).

Answer

\(1\). Fractions are preferable because \(\frac{1}{3}\) is a repeating decimal.
5106917
Consider the expressions. A: \(0.45 + \frac{1}{4} + 0.3\) B: \(\frac{2}{3} + 0.5 + \frac{1}{6}\) C: \(\frac{2}{5} + 1.2 - 0.35\) a) Which expression cannot be evaluated exactly using only terminating decimals? Explain. b) Evaluate that expression as a fraction in simplest form.

Hints

- Determine which fractions have terminating decimal representations. - A repeating decimal cannot be written exactly as a terminating decimal. - Convert the decimal in B to a fraction and use a common denominator.

Solution

1. In A, \(\frac{1}{4} = 0.25\), and in C, \(\frac{2}{5} = 0.4\). These are terminating decimals. 2. In B, both \(\frac{2}{3}\) and \(\frac{1}{6}\) have repeating decimal representations, so using only terminating decimals would require rounding. 3. Convert \(0.5 = \frac{1}{2}\). Then \(\frac{2}{3} + \frac{1}{2} + \frac{1}{6} = \frac{4}{6} + \frac{3}{6} + \frac{1}{6} = \frac{8}{6} = \frac{4}{3}\).

Answer

a) Expression B b) \(\frac{4}{3}\)
5106937
A student evaluates \(S = \frac{4}{9} + 0.3 + \frac{5}{9}\) and reports \(1.29\). The student used \(\frac{4}{9} \approx 0.44\) and \(\frac{5}{9} \approx 0.55\), then added the decimals. a) Explain why the result is not exact. b) Show an exact method that avoids rounding and uses properties of addition.

Hints

- Rounding during a calculation can change the final value. - Look for fractions with the same denominator that combine to a whole. - You may reorder and regroup addends.

Solution

1. The fractions have repeating decimal representations. The student truncated both decimals, losing information. Also, \(\frac{5}{9}\) rounded to the nearest hundredth is \(0.56\), not \(0.55\); either rounded calculation would still be approximate. 2. Use the commutative and associative properties to add the fractions first: \(\left(\frac{4}{9} + \frac{5}{9}\right) + 0.3\). 3. Evaluate exactly: \(\frac{9}{9} + 0.3 = 1.3\).

Answer

a) The student used truncated repeating decimals, so the sum is not exact. b) \(\frac{4}{9} + \frac{5}{9} = 1\), so \(S = 1.3\).
5112897
Sometimes changing forms makes an exact calculation much easier. a) \(\frac{1}{6} + 0.2\). Explain why using only terminating decimals cannot give an exact calculation. b) \(0.\overline{7} + \frac{2}{9}\).

Hints

- Examine the decimal representation of \(\frac{1}{6}\). - Convert \(0.\overline{7}\) to a fraction.

Solution

1. For a), write \(0.2 = \frac{1}{5}\). Then \(\frac{1}{6} + \frac{1}{5} = \frac{5}{30} + \frac{6}{30} = \frac{11}{30}\). The decimal representation of \(\frac{1}{6}\) repeats, so any terminating decimal used in its place would be rounded. 2. For b), write \(0.\overline{7} = \frac{7}{9}\). Then \(\frac{7}{9} + \frac{2}{9} = 1\).

Answer

a) \(\frac{11}{30}\); \(\frac{1}{6}\) does not have a terminating decimal representation. b) \(1\)
5113007
Consider the expression \(\frac{7}{9} - 0.25 \div \frac{3}{4}\). a) Evaluate the expression exactly by converting the decimal to a fraction. b) Explain why using only terminating decimals is not a useful way to calculate the entire expression exactly.

Hints

- Apply division before subtraction. - Convert every value to a form that supports an exact calculation. - Examine the decimal representation of \(\frac{7}{9}\).

Solution

1. Convert \(0.25\) to \(\frac{1}{4}\). 2. Perform the division first: \(\frac{1}{4} \div \frac{3}{4} = \frac{1}{4} \cdot \frac{4}{3} = \frac{1}{3}\). 3. Subtract: \(\frac{7}{9} - \frac{1}{3} = \frac{7}{9} - \frac{3}{9} = \frac{4}{9}\). 4. Both \(\frac{7}{9} = 0.\overline{7}\) and \(\frac{1}{3} = 0.\overline{3}\) have repeating decimal representations. Replacing them with terminating decimals would require rounding and would not preserve the exact value.

Answer

a) \(\frac{4}{9}\) b) \(\frac{7}{9}\) and \(\frac{1}{3}\) have repeating decimal representations, so terminating decimal approximations would not produce an exact calculation.
5113017
Consider the expression \(0.375 \div \frac{3}{4} + \frac{1}{2}\). Show two methods. Method 1: Convert \(\frac{3}{4}\) and \(\frac{1}{2}\) to decimals. Method 2: Convert \(0.375\) to a fraction. State which method you find easier and explain why.

Hints

- Recall the fraction equivalent of \(0.375\). - Complete both methods before comparing them. - Compare \(0.375\) with \(0.75\).

Solution

1. Method 1: Write \(\frac{3}{4} = 0.75\) and \(\frac{1}{2} = 0.5\). Then \(0.375 \div 0.75 = 0.5\), and \(0.5 + 0.5 = 1\). 2. Method 2: Write \(0.375 = \frac{3}{8}\). Then \(\frac{3}{8} \div \frac{3}{4} = \frac{3}{8} \cdot \frac{4}{3} = \frac{1}{2}\), and \(\frac{1}{2} + \frac{1}{2} = 1\). 3. Both methods are valid. The fraction method may feel easier because common factors simplify immediately; the decimal method may feel easier if you recognize that \(0.375\) is half of \(0.75\).

Answer

Both methods give \(1\). A valid explanation should compare the simplification in the fraction method with the recognizable decimal relationship in the decimal method.
5113727
Convert each fraction or mixed number to a decimal. a) \(\frac{9}{20}\) b) \(\frac{3}{8}\) c) \(2\frac{1}{4}\)

Hints

- Try rewriting each denominator as \(10\), \(100\), or \(1000\). - You can also divide the numerator by the denominator.

Solution

1. For a), rewrite the fraction with a denominator of \(100\): \(\frac{9}{20} = \frac{45}{100} = 0.45\). 2. For b), divide the numerator by the denominator: \(3 \div 8 = 0.375\). Equivalently, \(\frac{3}{8} = \frac{375}{1000}\). 3. For c), \(\frac{1}{4} = \frac{25}{100} = 0.25\). Therefore, \(2\frac{1}{4} = 2.25\).

Answer

a) \(0.45\) b) \(0.375\) c) \(2.25\)
5113737
Insert \(<\), \(>\), or \(=\) in each blank. Justify each comparison by converting one number to the other form. a) \(0.4 \;\square\; \frac{2}{5}\) b) \(0.33 \;\square\; \frac{1}{3}\) c) \(0.85 \;\square\; \frac{17}{20}\)

Hints

- Convert each pair to the same form before comparing. - Pay attention to whether a fraction has a terminating or repeating decimal form.

Solution

1. For a), \(\frac{2}{5} = \frac{4}{10} = 0.4\), so the values are equal. 2. For b), \(\frac{1}{3} = 0.3333\ldots\), while \(0.33 = 0.3300\ldots\). Therefore, \(0.33 < \frac{1}{3}\). 3. For c), \(\frac{17}{20} = \frac{85}{100} = 0.85\), so the values are equal.

Answer

a) \(0.4 = \frac{2}{5}\) b) \(0.33 < \frac{1}{3}\) c) \(0.85 = \frac{17}{20}\)
5117867
Write each fraction as a decimal. Use repeating-decimal notation when needed. a) \(\frac{9}{20}\) b) \(\frac{5}{6}\) c) \(\frac{4}{11}\) d) \(\frac{17}{50}\)

Hints

- Try rewriting a denominator as a power of ten. - When that is not possible, divide the numerator by the denominator. - Watch for repeated remainders during division.

Solution

1. For a), \(\frac{9}{20} = \frac{45}{100} = 0.45\). 2. For b), \(5 \div 6 = 0.8333\ldots = 0.8\overline{3}\). 3. For c), \(4 \div 11 = 0.3636\ldots = 0.\overline{36}\). 4. For d), \(\frac{17}{50} = \frac{34}{100} = 0.34\).

Answer

a) \(0.45\) b) \(0.8\overline{3}\) c) \(0.\overline{36}\) d) \(0.34\)
5118657
Write each missing equivalent form. Write fractions in simplest form. a) \(0.625=\square\) as a fraction b) \(\frac{2}{5}=\square\) as a decimal c) \(2.4=\square\) as a fraction d) \(-\frac{3}{8}=\square\) as a decimal

Hints

- Write a terminating decimal as a fraction with denominator \(10\), \(100\), or \(1000\). - Simplify every fraction completely. - A denominator of \(8\) can be changed to \(1000\).

Solution

1. For (1), \(0.625 = \frac{625}{1000}\). Divide the numerator and denominator by \(125\): \(\frac{625}{1000} = \frac{5}{8}\). 2. For (2), \(\frac{2}{5} = \frac{4}{10} = 0.4\). 3. For (3), \(2.4 = \frac{24}{10} = \frac{12}{5}\). 4. For (4), \(-\frac{3}{8} = -\frac{375}{1000} = -0.375\).

Answer

a) \(\frac{5}{8}\) b) \(0.4\) c) \(\frac{12}{5}\) d) \(-0.375\)
5119027
Convert each fraction to a decimal by first rewriting it with a denominator of \(10\), \(100\), or \(1000\). a) \(\frac{3}{5}\) b) \(\frac{7}{20}\) c) \(\frac{9}{40}\) d) \(\frac{11}{250}\)

Hints

- Find a factor that changes each denominator to \(10\), \(100\), or \(1000\). - Multiply the numerator by the same factor. - Use the number of zeros in the denominator to place the decimal point.

Solution

1. For a), multiply the numerator and denominator by \(2\): \(\frac{3}{5} = \frac{6}{10} = 0.6\). 2. For b), multiply the numerator and denominator by \(5\): \(\frac{7}{20} = \frac{35}{100} = 0.35\). 3. For c), multiply the numerator and denominator by \(25\): \(\frac{9}{40} = \frac{225}{1000} = 0.225\). 4. For d), multiply the numerator and denominator by \(4\): \(\frac{11}{250} = \frac{44}{1000} = 0.044\).

Answer

a) \(0.6\) b) \(0.35\) c) \(0.225\) d) \(0.044\)
5119037
Order the numbers from least to greatest: \(\frac{3}{8}\), \(0.38\), \(\frac{2}{5}\), \(0.42\)

Hints

- Convert all numbers to the same form before comparing them. - Add trailing zeros so the decimals have the same number of places.

Solution

1. Convert the fractions to decimals: \(\frac{3}{8} = 3 \div 8 = 0.375\) and \(\frac{2}{5} = \frac{4}{10} = 0.4\). 2. Compare all four decimals: \(0.375 < 0.380 < 0.400 < 0.420\). 3. Replace the converted decimals with the original fractions: \(\frac{3}{8} < 0.38 < \frac{2}{5} < 0.42\).

Answer

\(\frac{3}{8} < 0.38 < \frac{2}{5} < 0.42\)
5119047
Find the missing number in each equation. a) \(\frac{\square}{8} = 0.375\) b) \(0.64 = \frac{\square}{25}\) c) \(\frac{7}{\square} = 0.07\)

Hints

- Write each decimal as a fraction with denominator \(10\), \(100\), or \(1000\). - Simplify or scale the fraction to match the given denominator or numerator. - Compare corresponding parts of equivalent fractions.

Solution

1. For a), \(0.375 = \frac{375}{1000} = \frac{3}{8}\), so \(\square = 3\). 2. For b), \(0.64 = \frac{64}{100} = \frac{16}{25}\), so \(\square = 16\). 3. For c), \(0.07 = \frac{7}{100}\). Comparing \(\frac{7}{\square}\) with \(\frac{7}{100}\) gives \(\square = 100\).

Answer

a) \(\square = 3\) b) \(\square = 16\) c) \(\square = 100\)
5127977
Evaluate each expression using the most convenient fraction or decimal form. Give each answer as both a fraction and a decimal. a) \(0.25\cdot\frac{4}{7}\) b) \(\frac{3}{4}+0.125-\frac{1}{8}\) c) \(0.6\div\frac{2}{3}\)

Hints

- Recognize common fraction-decimal equivalents. - In part b), look for terms that become additive inverses after conversion. - Convert the decimal to a fraction before dividing in part c).

Solution

1. For a), write \(0.25=\frac{1}{4}\). Then \(\frac{1}{4}\cdot\frac{4}{7}=\frac{1}{7}=0.\overline{142857}\). 2. For b), write \(0.125=\frac{1}{8}\). Then \(\frac{3}{4}+\frac{1}{8}-\frac{1}{8}=\frac{3}{4}=0.75\). 3. For c), write \(0.6=\frac{3}{5}\). Then \(\frac{3}{5}\div\frac{2}{3}=\frac{3}{5}\cdot\frac{3}{2}=\frac{9}{10}=0.9\).

Answer

a) \(\frac{1}{7}=0.\overline{142857}\) b) \(\frac{3}{4}=0.75\) c) \(\frac{9}{10}=0.9\)
5128287
Use long division to convert each fraction to a decimal. State whether the decimal terminates or repeats. a) \(\frac{3}{16}\) b) \(\frac{5}{6}\) c) \(\frac{4}{11}\)

Hints

- Divide each numerator by its denominator. - A remainder of zero means the decimal terminates. - A repeated remainder means the decimal repeats.

Solution

1. For a), \(3 \div 16 = 0.1875\). The remainder becomes zero, so the decimal terminates. 2. For b), \(5 \div 6 = 0.8333\ldots = 0.8\overline{3}\). A remainder repeats, so the decimal repeats. 3. For c), \(4 \div 11 = 0.3636\ldots = 0.\overline{36}\). The remainders cycle, so the decimal repeats.

Answer

a) \(0.1875\), terminating b) \(0.8\overline{3}\), repeating c) \(0.\overline{36}\), repeating
5128367
Insert \(<\), \(>\), or \(=\). Convert each fraction to a decimal before comparing. a) \(\frac{7}{10} \;\square\; 0.75\) b) \(0.4 \;\square\; \frac{1}{4}\) c) \(\frac{12}{50} \;\square\; 0.24\) d) \(1.3 \;\square\; \frac{6}{5}\)

Hints

- Convert both numbers in each pair to decimal form. - Compare decimal digits by place value. - Try scaling a denominator to \(10\) or \(100\).

Solution

1. For a), \(\frac{7}{10} = 0.7\). Since \(0.7 < 0.75\), the correct symbol is \(<\). 2. For b), \(\frac{1}{4} = 0.25\). Since \(0.4 > 0.25\), the correct symbol is \(>\). 3. For c), \(\frac{12}{50} = \frac{24}{100} = 0.24\). The values are equal. 4. For d), \(\frac{6}{5} = \frac{12}{10} = 1.2\). Since \(1.3 > 1.2\), the correct symbol is \(>\).

Answer

a) \(<\) b) \(>\) c) \(=\) d) \(>\)
5154777
Consider \(\frac{7}{20}\), \(\frac{5}{6}\), \(\frac{11}{40}\), and \(\frac{2}{3}\). Which fractions have terminating decimal forms? Give those decimal values, and briefly explain why the other fractions do not terminate.

Hints

- Factor each denominator after simplifying the fraction. - Only factors of \(2\) and \(5\) allow a terminating decimal. - You may also check by dividing the numerator by the denominator.

Solution

1. A simplified fraction has a terminating decimal when its denominator has no prime factors other than \(2\) and \(5\). 2. For \(\frac{7}{20}\), \(20 = 2^2 \cdot 5\), so the decimal terminates: \(\frac{7}{20} = \frac{35}{100} = 0.35\). 3. For \(\frac{11}{40}\), \(40 = 2^3 \cdot 5\), so the decimal terminates: \(\frac{11}{40} = \frac{275}{1000} = 0.275\). 4. The denominators of \(\frac{5}{6}\) and \(\frac{2}{3}\) contain the prime factor \(3\) after simplification, so their decimals repeat.

Answer

\(\frac{7}{20} = 0.35\) and \(\frac{11}{40} = 0.275\) terminate. The fractions \(\frac{5}{6}\) and \(\frac{2}{3}\) repeat because their simplified denominators contain a factor of \(3\).
5318207
For each point \(A\), \(B\), \(C\), and \(D\), write the value as both a decimal and a fraction in simplest form or a mixed number.
Figure for problem 531820

Hints

- Determine the value of one small interval. - Points left of \(0\) have negative values. - Each interval represents one fourth, which can also be written as \(0.25\). - Simplify each fraction.

Solution

1. There are \(4\) equal intervals from \(0\) to \(1\), so each interval represents \(0.25=\frac{1}{4}\). 2. Point \(A\) is \(-1.25=-1\frac{1}{4}=-\frac{5}{4}\). 3. Point \(B\) is \(-0.5=-\frac{1}{2}\). 4. Point \(C\) is \(0.75=\frac{3}{4}\). 5. Point \(D\) is \(1.5=1\frac{1}{2}=\frac{3}{2}\).

Answer

\(A=-1.25=-1\frac{1}{4}\), \(B=-0.5=-\frac{1}{2}\), \(C=0.75=\frac{3}{4}\), \(D=1.5=1\frac{1}{2}\)
5353317
For each marked point, write the rational number as both a decimal and a fraction in simplest form.
Figure for problem 535331

Hints

- Determine the value of one small interval. - Write each decimal as a fraction with denominator \(10\), \(100\), or \(1000\). - Simplify each fraction.

Solution

1. From \(0\) to \(0.5\), there are \(4\) equal intervals, so each interval represents \(0.5\div4=0.125=\frac{1}{8}\). 2. Point \(A\) is \(-0.75=-\frac{3}{4}\). 3. Point \(B\) is \(-0.375=-\frac{3}{8}\). 4. Point \(C\) is \(0.125=\frac{1}{8}\). 5. Point \(D\) is \(0.5=\frac{1}{2}\). 6. Point \(E\) is \(0.875=\frac{7}{8}\).

Answer

\(A=-0.75=-\frac{3}{4}\), \(B=-0.375=-\frac{3}{8}\), \(C=0.125=\frac{1}{8}\), \(D=0.5=\frac{1}{2}\), \(E=0.875=\frac{7}{8}\)
5353327
For each letter on the number line, write the rational number as both a decimal and a fraction in simplest form.
Figure for problem 535332

Hints

- Determine the value of one interval from \(0\) to \(1\). - Count left for negative values and right for positive values. - Write tenths as fractions and simplify.

Solution

1. The interval from \(0\) to \(1\) is divided into \(5\) equal parts, so each interval represents \(0.2=\frac{1}{5}\). 2. Point \(P\) is \(-1.2=-\frac{6}{5}\). 3. Point \(Q\) is \(-0.8=-\frac{4}{5}\). 4. Point \(R\) is \(-0.4=-\frac{2}{5}\). 5. Point \(S\) is \(0.2=\frac{1}{5}\). 6. Point \(T\) is \(0.6=\frac{3}{5}\). 7. Point \(U\) is \(1.4=\frac{7}{5}\).

Answer

\(P=-1.2=-\frac{6}{5}\), \(Q=-0.8=-\frac{4}{5}\), \(R=-0.4=-\frac{2}{5}\), \(S=0.2=\frac{1}{5}\), \(T=0.6=\frac{3}{5}\), \(U=1.4=\frac{7}{5}\)
5353947
Convert \(-\frac{1}{3}\), \(-\frac{5}{6}\), and \(-1\frac{1}{2}\) to decimals. Then match each value to point \(A\), \(B\), or \(C\) on the number line.
Figure for problem 535394

Hints

- Divide each numerator by its denominator. - Note whether the decimal terminates or repeats. - Order the three negative values before matching them to the number line. - Values farther left are smaller.

Solution

1. Convert the mixed number: \(-1\frac{1}{2} = -1.5\). 2. Convert the fractions: \(-\frac{5}{6} = -0.8333\ldots = -0.8\overline{3}\) and \(-\frac{1}{3} = -0.3333\ldots = -0.\overline{3}\). 3. On the number line, point \(A\) is at \(-1.5\), point \(B\) is at about \(-0.83\), and point \(C\) is at about \(-0.33\). 4. Therefore, \(A\) matches \(-1\frac{1}{2}\), \(B\) matches \(-\frac{5}{6}\), and \(C\) matches \(-\frac{1}{3}\).

Answer

\(-1\frac{1}{2} = -1.5\), point \(A\) \(-\frac{5}{6} = -0.8\overline{3}\), point \(B\) \(-\frac{1}{3} = -0.\overline{3}\), point \(C\)
5358227
A painter primes a rectangular section that covers \(\frac{4}{5}\) of the wall’s width and \(\frac{3}{4}\) of its height, as shown. First convert both fractions to decimals and multiply. Then write the final result as a fraction in simplest form.
Figure for problem 535822

Hints

- Convert \(\frac{4}{5}\) and \(\frac{3}{4}\) to decimals. - Multiply the decimal values to find the fraction of the wall’s area. - Write the decimal product as a fraction with a power of \(10\) in the denominator, then simplify.

Solution

1. Convert the fractions: \(\frac{4}{5}=0.8\) and \(\frac{3}{4}=0.75\). 2. Multiply: \(0.8\cdot0.75=0.6\). 3. Convert back to a fraction: \(0.6=\frac{6}{10}=\frac{3}{5}\).

Answer

\(\frac{3}{5}\)
5104117
Lucas makes this claim: “If \(\frac{1}{n}\), where \(n\) is a positive whole number, has a repeating decimal form, then \(\frac{k}{n}\) must also have a repeating decimal form for every positive whole number \(k\).” Is Lucas correct? Justify your answer with an example or counterexample.

Hints

- One counterexample is enough to disprove a universal claim. - Look for a numerator that cancels a prime factor in the denominator. - Try a small denominator such as \(3\), \(6\), or \(7\). - After simplifying, check which prime factors remain in the denominator.

Solution

1. If \(\frac{1}{n}\) repeats, then the prime factorization of \(n\) includes at least one prime other than \(2\) or \(5\). 2. However, a numerator \(k\) may share that factor with \(n\), allowing it to cancel when the fraction is simplified. 3. For example, \(\frac{1}{6} = 0.1\overline{6}\), so \(\frac{1}{6}\) repeats. 4. Choose \(k = 3\). Then \(\frac{3}{6} = \frac{1}{2} = 0.5\), which terminates. 5. This counterexample proves that Lucas's claim is false.

Answer

Lucas is not correct. For example, \(\frac{1}{6} = 0.1\overline{6}\) repeats, but \(\frac{3}{6} = \frac{1}{2} = 0.5\) terminates because the factor \(3\) cancels.
5104657
For a fraction in simplest form with a terminating decimal, the number of decimal places equals the greater exponent of \(2\) and \(5\) in the denominator. For example, \(\frac{1}{8} = \frac{1}{2^3} = 0.125\), which has \(3\) decimal places. Find every two-digit positive whole number \(n\) for which \(\frac{1}{n}\) has a terminating decimal with exactly four decimal places.

Hints

- Exactly four decimal places means the larger exponent of \(2\) and \(5\) is \(4\). - Consider separately the cases where the exponent of \(2\) is \(4\) and where the exponent of \(5\) is \(4\). - Keep only two-digit results.

Solution

1. Write \(n = 2^a \cdot 5^b\). Exactly four decimal places requires \(\max(a,b) = 4\). 2. If \(a = 4\), then \(n = 16 \cdot 5^b\). For \(b = 0\), \(n = 16\). For \(b = 1\), \(n = 80\). For \(b \ge 2\), \(n\) is at least \(400\). 3. If \(b = 4\), then \(n = 625 \cdot 2^a\), which is never two-digit. 4. Therefore, the only two-digit values are \(16\) and \(80\). 5. Check: \(\frac{1}{16} = 0.0625\) and \(\frac{1}{80} = 0.0125\), each with four decimal places.

Answer

\(16\) and \(80\)
5105017
Compare the decimal forms of \(A = \frac{4}{11}\) and \(B = \frac{5}{13}\). a) Find the repeating decimal for each fraction. b) Which fraction has the longer repeating block? c) How many digits are in the repeating block of \(B\)?

Hints

- Continue long division until a remainder repeats. - The digits produced before the remainder cycle restarts form the repeating block. - Count the digits under each repeating bar.

Solution

1. For \(A\), \(4 \div 11 = 0.3636\ldots = 0.\overline{36}\). Its repeating block has \(2\) digits. 2. For \(B\), long division gives the digits \(3, 8, 4, 6, 1, 5\) before the first remainder returns. Thus, \(\frac{5}{13} = 0.\overline{384615}\). 3. The repeating block of \(B\) has \(6\) digits, so it is longer than the \(2\)-digit repeating block of \(A\).

Answer

a) \(A = 0.\overline{36}\); \(B = 0.\overline{384615}\) b) \(B\) has the longer repeating block. c) The repeating block of \(B\) has \(6\) digits.
5105107
Analyze each statement. Decide whether it is true. If it is false, correct it and briefly explain why. a) \(0.\overline{12} = \frac{12}{90}\) b) \(\frac{5}{11} = 0.\overline{45}\), so \(\frac{5}{110} = 0.0\overline{45}\). c) \(0.\overline{9} < 1\) d) \(\frac{1}{6}\) is greater than \(0.16\).

Hints

- For a repeating block with two digits, think about a denominator made of two nines. - Consider what dividing a decimal by \(10\) does to its digits. - Try assigning a variable to \(0.\overline{9}\) and multiplying by \(10\). - Write \(\frac{1}{6}\) as a decimal and compare digits from left to right.

Solution

1. Statement a) is false. A two-digit repeating block that begins immediately corresponds to a denominator of \(99\): \(0.\overline{12} = \frac{12}{99} = \frac{4}{33}\). 2. Statement b) is true. Since \(\frac{5}{11} = 0.\overline{45}\), dividing by \(10\) shifts every digit one place to the right: \(\frac{5}{110} = 0.0\overline{45}\). 3. Statement c) is false. Let \(x = 0.\overline{9}\). Then \(10x = 9.\overline{9}\), so \(9x = 9\) and \(x = 1\). Therefore, \(0.\overline{9} = 1\). 4. Statement d) is true. Since \(\frac{1}{6} = 0.1666\ldots\), it is greater than \(0.1600\ldots\).

Answer

a) False. \(0.\overline{12} = \frac{12}{99} = \frac{4}{33}\). b) True. c) False. \(0.\overline{9} = 1\). d) True. \(\frac{1}{6} = 0.1\overline{6} > 0.16\).
5105137
A student proposes this rule: “If the denominator of a fraction is divisible by \(3\), then its decimal form always repeats.” a) Give a counterexample showing that the rule is not always true. b) Rewrite the rule so that it is mathematically correct. c) For \(\frac{k}{120}\), where \(1 \le k < 120\), which numerators \(k\) produce a terminating decimal even though \(120\) is divisible by \(3\)? Describe the required property of \(k\).

Hints

- Find a fraction whose factor of \(3\) cancels. - The denominator must be examined after the fraction is simplified. - Factor \(120\) and identify the factor that must cancel.

Solution

1. For a), \(\frac{3}{6} = \frac{1}{2} = 0.5\). The original denominator is divisible by \(3\), but the decimal terminates. 2. For b), a fraction has a repeating decimal exactly when its denominator, after the fraction is simplified, has a prime factor other than \(2\) or \(5\). 3. For c), \(120 = 2^3 \cdot 3 \cdot 5\). The factor \(3\) must cancel for the simplified denominator to contain only \(2\) and \(5\). 4. Therefore, \(k\) must be divisible by \(3\). Every multiple of \(3\) from \(3\) through \(117\) works.

Answer

a) One counterexample is \(\frac{3}{6} = 0.5\). b) A fraction repeats exactly when its simplified denominator has a prime factor other than \(2\) or \(5\). c) \(k\) must be a multiple of \(3\).
5105217
The decimal form of \(\frac{1}{7}\) is \(0.\overline{142857}\). a) Find the decimal forms of \(\frac{2}{7}\) and \(\frac{3}{7}\) without completing full long division. Explain how the digit pattern helps. b) In the repeating block \(142857\), add the first digit to the fourth, the second to the fifth, and the third to the sixth. What do you notice?

Hints

- Arrange the digits of \(142857\) in a cycle. - Use the first decimal digit of each quotient to choose where the cycle begins. - Split the six-digit block into two halves and compare corresponding positions.

Solution

1. The repeating blocks for fractions with denominator \(7\) are cyclic shifts of \(142857\). 2. Since \(2 \div 7\) begins with \(0.2\ldots\), start the cycle with \(2\): \(\frac{2}{7} = 0.\overline{285714}\). 3. Since \(3 \div 7\) begins with \(0.4\ldots\), start the cycle with \(4\): \(\frac{3}{7} = 0.\overline{428571}\). 4. Pairing opposite positions gives \(1 + 8 = 9\), \(4 + 5 = 9\), and \(2 + 7 = 9\). Every pair sums to \(9\).

Answer

a) \(\frac{2}{7} = 0.\overline{285714}\) and \(\frac{3}{7} = 0.\overline{428571}\) b) Each paired sum is \(9\): \(1 + 8 = 9\), \(4 + 5 = 9\), and \(2 + 7 = 9\).
5105707
Explore fractions whose denominators contain nines and zeros. a) Test the idea that the number of nines in a denominator gives the length of the repeating block for a repeating decimal that begins immediately. Use \(\frac{13}{99}\) and \(\frac{123}{999}\). b) Explain how the decimal changes when \(\frac{13}{99}\) is replaced by \(\frac{13}{990}\). c) Which fraction has decimal form \(0.0\overline{07}\)?

Hints

- Compare the number of nines with the number of digits in each repeating block. - A zero added to the denominator multiplies it by \(10\). - Rewrite \(0.0\overline{07}\) as \(0.\overline{07} \div 10\).

Solution

1. For a), \(\frac{13}{99} = 0.\overline{13}\), with a two-digit repeating block, and \(\frac{123}{999} = 0.\overline{123}\), with a three-digit repeating block. These examples support the idea. 2. For b), \(\frac{13}{990} = \frac{13}{99} \div 10\). The digits shift one place to the right, giving \(0.0\overline{13}\). 3. For c), \(0.\overline{07} = \frac{7}{99}\). Dividing by \(10\) gives \(0.0\overline{07} = \frac{7}{990}\).

Answer

a) \(\frac{13}{99} = 0.\overline{13}\); \(\frac{123}{999} = 0.\overline{123}\) b) The repeating block shifts one place to the right: \(\frac{13}{990} = 0.0\overline{13}\). c) \(\frac{7}{990}\)
5105857
Analyze the fractions \(\frac{36}{48}\), \(\frac{36}{45}\), and \(\frac{36}{54}\). 1. Write each fraction in simplest form. 2. Decide whether each decimal form terminates or repeats. 3. Find each decimal form.

Hints

- First write each fraction in simplest form. - A fraction in simplest form has a terminating decimal when its denominator has no prime factors other than \(2\) and \(5\). - In long division, a repeated remainder produces a repeating decimal.

Solution

1. For \(\frac{36}{48}\), divide the numerator and denominator by \(12\): \(\frac{36}{48} = \frac{3}{4}\). The denominator \(4\) has only the prime factor \(2\), so the decimal terminates. The value is \(0.75\). 2. For \(\frac{36}{45}\), divide the numerator and denominator by \(9\): \(\frac{36}{45} = \frac{4}{5}\). The denominator \(5\) has only the prime factor \(5\), so the decimal terminates. The value is \(0.8\). 3. For \(\frac{36}{54}\), divide the numerator and denominator by \(18\): \(\frac{36}{54} = \frac{2}{3}\). The denominator has a prime factor other than \(2\) or \(5\), so the decimal repeats. The value is \(0.\overline{6}\).

Answer

\(\frac{36}{48} = \frac{3}{4} = 0.75\), terminating \(\frac{36}{45} = \frac{4}{5} = 0.8\), terminating \(\frac{36}{54} = \frac{2}{3} = 0.\overline{6}\), repeating
5105907
Consider the fraction \(\frac{21}{n \cdot 125}\). For which values \(n \in \{3, 4, 9, 11, 14\}\) does the fraction have a terminating decimal form? Justify your choices.

Hints

- Factor the numerator and denominator. - A simplified denominator may contain only \(2\) and \(5\) for the decimal to terminate. - Check whether each extra prime factor in \(n\) cancels completely with \(21\).

Solution

1. Factor the fixed parts: \(21 = 3 \cdot 7\) and \(125 = 5^3\). 2. After simplification, the denominator may contain only prime factors of \(2\) and \(5\). 3. If \(n = 3\), the factor \(3\) cancels, leaving denominator \(5^3\), so the decimal terminates. 4. If \(n = 4 = 2^2\), the denominator contains only factors of \(2\) and \(5\), so the decimal terminates. 5. If \(n = 9 = 3^2\), only one factor of \(3\) cancels, so a factor of \(3\) remains. The decimal repeats. 6. If \(n = 11\), the factor \(11\) remains in the denominator. The decimal repeats. 7. If \(n = 14 = 2 \cdot 7\), the factor \(7\) cancels, leaving only factors of \(2\) and \(5\). The decimal terminates.

Answer

\(n = 3\), \(4\), or \(14\)
5139417
Complete the table by filling in the missing equivalent forms. Write each fraction in simplest form. <table> <tr> <th>Fraction</th> <th>Decimal</th> <th>Percent</th> </tr> <tr> <td>\(\frac{1}{400}\)</td> <td></td> <td></td> </tr> <tr> <td></td> <td></td> <td>\(0.4\%\)</td> </tr> <tr> <td></td> <td>\(0.125\)</td> <td></td> </tr> <tr> <td>\(\frac{5}{6}\)</td> <td></td> <td></td> </tr> </table> Briefly explain why the decimal form of \(\frac{5}{6}\) does not terminate.

Hints

- To convert a decimal to a percent, multiply by \(100\). - A percent such as \(0.4\%\) is less than \(1\%\), so its decimal form must be less than \(0.01\). - Use division to convert a fraction to a decimal. - Consider which prime factors a reduced denominator may have for its decimal form to terminate.

Solution

1. Row 1: \(\frac{1}{400} = 1 \div 400 = 0.0025\). As a percent, \(0.0025 \cdot 100 = 0.25\%\). 2. Row 2: \(0.4\% = \frac{0.4}{100} = 0.004\). As a fraction, \(0.004 = \frac{4}{1000} = \frac{1}{250}\). 3. Row 3: \(0.125 = 12.5\%\). As a fraction, \(0.125 = \frac{125}{1000} = \frac{1}{8}\). 4. Row 4: \(\frac{5}{6} = 5 \div 6 = 0.8\overline{3}\). As a percent, this is \(83.\overline{3}\%\). 5. In lowest terms, the denominator \(6\) contains the prime factor \(3\). Because the denominator has a prime factor other than \(2\) or \(5\), its decimal form repeats instead of terminating.

Answer

\(\frac{1}{400} = 0.0025 = 0.25\%\) \(\frac{1}{250} = 0.004 = 0.4\%\) \(\frac{1}{8} = 0.125 = 12.5\%\) \(\frac{5}{6} = 0.8\overline{3} = 83.\overline{3}\%\) The decimal for \(\frac{5}{6}\) repeats because its reduced denominator contains the prime factor \(3\).

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