Aimathic
Login | English | Deutsch

Free Math Worksheets

Build your own math worksheets from 21,000 problems for grades 3 to 12, from fractions to calculus. Every problem includes step-by-step solutions.

Percent as rate per 100

Click problems to add them to your worksheet.

5100496
\(12\%\) is equivalent to which fraction? a) \(\frac{1}{2}\) b) \(\frac{1}{12}\) c) \(\frac{3}{25}\) d) \(\frac{6}{25}\)

Hints

- What does “percent” mean? - First write the percent as a fraction with denominator \(100\). - Simplify the fraction as much as possible.

Solution

1. Write the percent as a fraction with denominator \(100\): \(12\% = \frac{12}{100}\). 2. Simplify the fraction: \(\frac{12}{100} = \frac{3}{25}\) by dividing the numerator and denominator by \(4\).

Answer

c) \(\frac{3}{25}\)
5118096
What percent is equivalent to \(\frac{7}{20}\)?

Hints

- Can you write the fraction with denominator \(100\)? - What does the numerator mean when the denominator is \(100\)?

Solution

1. Multiply the numerator and denominator by \(5\): \(\frac{7}{20} = \frac{35}{100}\). 2. The fraction \(\frac{35}{100}\) is equivalent to \(35\%\).

Answer

\(35\%\)
5357696
What percent of the strip is shaded?
Figure for problem 535769

Hints

- How many equal parts are in the strip? - How many parts are shaded? - Write the shaded portion as a fraction first. - How do you convert fourths to percents?

Solution

1. The strip has \(4\) equal parts. 2. Three parts are shaded. 3. The shaded portion is \(\frac{3}{4}\). 4. Convert to a percent: \(\frac{3}{4} = \frac{75}{100} = 75\%\).

Answer

\(75\%\) of the strip is shaded.
5357706
What percent of the circle is shaded?
Figure for problem 535770

Hints

- Count all the equal sectors in the circle. - How many sectors are shaded? - Write the fraction with denominator \(100\).

Solution

1. The circle is divided into \(5\) equal sectors. 2. Two sectors are shaded. 3. The shaded portion is \(\frac{2}{5}\). 4. Convert to a percent: \(\frac{2}{5} = \frac{40}{100} = 40\%\).

Answer

\(40\%\) of the circle is shaded.
5102116
Write each percent as a fraction in simplest form: \(12\%\), \(45\%\), \(125\%\), \(8\%\).

Hints

- What does “percent” mean? - Write each percent as a fraction with denominator \(100\). - What common factors do the numerator and denominator have?

Solution

1. For \(12\%\): \(\frac{12}{100} = \frac{3}{25}\) after dividing by \(4\). 2. For \(45\%\): \(\frac{45}{100} = \frac{9}{20}\) after dividing by \(5\). 3. For \(125\%\): \(\frac{125}{100} = \frac{5}{4}\) after dividing by \(25\). 4. For \(8\%\): \(\frac{8}{100} = \frac{2}{25}\) after dividing by \(4\).

Answer

\(12\% = \frac{3}{25}\) \(45\% = \frac{9}{20}\) \(125\% = \frac{5}{4}\) \(8\% = \frac{2}{25}\)
5102236
For each fraction, first write an equivalent fraction with denominator \(100\). Then write the value as a percent. Finally, order the three values from least to greatest: \(\frac{3}{4}\), \(\frac{18}{60}\), and \(\frac{11}{20}\).

Hints

- What can you multiply each denominator by to get \(100\)? - It may help to simplify a fraction before writing an equivalent fraction with denominator \(100\). - Percent means “per hundred.”

Solution

1. Multiply the numerator and denominator of \(\frac{3}{4}\) by \(25\): \(\frac{3}{4} = \frac{75}{100} = 75\%\). 2. Simplify \(\frac{18}{60}\) by dividing by \(6\), then multiply the numerator and denominator by \(10\): \(\frac{18}{60} = \frac{3}{10} = \frac{30}{100} = 30\%\). 3. Multiply the numerator and denominator of \(\frac{11}{20}\) by \(5\): \(\frac{11}{20} = \frac{55}{100} = 55\%\). 4. Compare the percents: \(30\% < 55\% < 75\%\).

Answer

\(\frac{3}{4} = \frac{75}{100} = 75\%\) \(\frac{18}{60} = \frac{30}{100} = 30\%\) \(\frac{11}{20} = \frac{55}{100} = 55\%\) Order: \(30\% < 55\% < 75\%\)
5102356
Simplify each fraction completely, then write it as a percent. Order the results from least to greatest: \(\frac{48}{64}\); \(\frac{126}{140}\); \(\frac{81}{108}\)

Hints

- How can the greatest common factor help you simplify each fraction? - How can you write three fourths or nine tenths as hundredths? - You can compare the fractions by writing them as decimals or percents.

Solution

1. The greatest common factor of \(48\) and \(64\) is \(16\). Thus, \(\frac{48}{64} = \frac{3}{4} = 0.75 = 75\%\). 2. The greatest common factor of \(126\) and \(140\) is \(14\). Thus, \(\frac{126}{140} = \frac{9}{10} = 0.9 = 90\%\). 3. The greatest common factor of \(81\) and \(108\) is \(27\). Thus, \(\frac{81}{108} = \frac{3}{4} = 0.75 = 75\%\). 4. Compare the percents: \(75\% = 75\% < 90\%\).

Answer

\(\frac{48}{64} = 75\%\) \(\frac{126}{140} = 90\%\) \(\frac{81}{108} = 75\%\) Order: \(\frac{48}{64} = \frac{81}{108} < \frac{126}{140}\), or \(75\% = 75\% < 90\%\)
5104066
Write each fraction as a percent: a) \(\frac{3}{4}\) b) \(\frac{7}{10}\) c) \(\frac{13}{20}\) d) \(\frac{18}{50}\) e) \(\frac{1}{5}\)

Hints

- What can you multiply each denominator by to get \(100\)? - Multiply the numerator by the same number. - A fraction with denominator \(100\) can be written directly as a percent.

Solution

1. Multiply the numerator and denominator of \(\frac{3}{4}\) by \(25\): \(\frac{3}{4} = \frac{75}{100} = 75\%\). 2. Multiply the numerator and denominator of \(\frac{7}{10}\) by \(10\): \(\frac{7}{10} = \frac{70}{100} = 70\%\). 3. Multiply the numerator and denominator of \(\frac{13}{20}\) by \(5\): \(\frac{13}{20} = \frac{65}{100} = 65\%\). 4. Multiply the numerator and denominator of \(\frac{18}{50}\) by \(2\): \(\frac{18}{50} = \frac{36}{100} = 36\%\). 5. Multiply the numerator and denominator of \(\frac{1}{5}\) by \(20\): \(\frac{1}{5} = \frac{20}{100} = 20\%\).

Answer

a) \(75\%\) b) \(70\%\) c) \(65\%\) d) \(36\%\) e) \(20\%\)
5104086
Write each fraction as a percent. Simplify or divide when the denominator cannot be changed to \(100\) easily. a) \(\frac{21}{70}\) b) \(\frac{12}{16}\) c) \(\frac{3}{8}\) d) \(\frac{24}{400}\)

Hints

- Can you simplify the fraction first? - When the denominator is greater than \(100\), can you divide it to get \(100\)? - Think about the decimal value of eighths.

Solution

1. Simplify \(\frac{21}{70}\) by dividing by \(7\): \(\frac{21}{70} = \frac{3}{10} = \frac{30}{100} = 30\%\). 2. Simplify \(\frac{12}{16}\) by dividing by \(4\): \(\frac{12}{16} = \frac{3}{4} = \frac{75}{100} = 75\%\). 3. Divide to convert \(\frac{3}{8}\) to a decimal: \(3 \div 8 = 0.375\). Therefore, \(\frac{3}{8} = 37.5\%\). 4. Divide the numerator and denominator of \(\frac{24}{400}\) by \(4\): \(\frac{24}{400} = \frac{6}{100} = 6\%\).

Answer

a) \(30\%\) b) \(75\%\) c) \(37.5\%\) d) \(6\%\)
5105626
Consider these four values: \(A = 0.8\) \(B = \frac{4}{5}\) \(C = 8\%\) \(D = \frac{80}{10}\) a) Which two values are equal? Explain by writing each value as a fraction with denominator \(100\). b) Explain the difference between \(A\) and \(C\).

Hints

- What denominator does the word “percent” represent? - How can you write a decimal with one decimal place as a fraction in tenths? - Multiply a fraction's numerator and denominator by the same number to make an equivalent fraction.

Solution

1. Write \(A = 0.8\) as hundredths: \(0.8 = \frac{8}{10} = \frac{80}{100}\). 2. Write \(B = \frac{4}{5}\) as hundredths: \(\frac{4}{5} = \frac{80}{100}\). 3. Write \(C = 8\%\) as hundredths: \(8\% = \frac{8}{100}\). 4. Write \(D = \frac{80}{10}\) as hundredths: \(\frac{80}{10} = \frac{800}{100}\). 5. Values \(A\) and \(B\) are equal because both are \(\frac{80}{100}\). 6. Value \(A\) is \(80\%\), while \(C\) is \(8\%\). Therefore, \(A\) is \(10\) times \(C\).

Answer

a) \(A\) and \(B\) are equal because \(0.8 = \frac{80}{100}\) and \(\frac{4}{5} = \frac{80}{100}\). b) \(A = 80\%\), while \(C = 8\%\). Therefore, \(A\) is \(10\) times \(C\).
5114496
Write each percent as a fraction in simplest form: a) \(20\%\) b) \(25\%\) c) \(15\%\) d) \(60\%\)

Hints

- What does “percent” mean? - First write each value as a fraction with denominator \(100\). - Is there a number that divides both the numerator and denominator?

Solution

1. Write each percent as a fraction with denominator \(100\): \(20\% = \frac{20}{100}\), \(25\% = \frac{25}{100}\), \(15\% = \frac{15}{100}\), and \(60\% = \frac{60}{100}\). 2. Simplify each fraction: a) \(\frac{20}{100} = \frac{1}{5}\) by dividing by \(20\). b) \(\frac{25}{100} = \frac{1}{4}\) by dividing by \(25\). c) \(\frac{15}{100} = \frac{3}{20}\) by dividing by \(5\). d) \(\frac{60}{100} = \frac{3}{5}\) by dividing by \(20\).

Answer

a) \(\frac{1}{5}\) b) \(\frac{1}{4}\) c) \(\frac{3}{20}\) d) \(\frac{3}{5}\)
5114506
Fill in each missing number so that the statement is true. a) \(\frac{2}{5} = \ldots\%\) b) \(18\% = \frac{\ldots}{50}\) c) \(\frac{7}{20} = \ldots\%\) d) \(88\% = \frac{\ldots}{25}\)

Hints

- How can you change a denominator of \(5\) or \(20\) to \(100\)? - When converting a percent to a fraction with a given denominator, first write the percent as a fraction over \(100\), then simplify.

Solution

1. For a), write the fraction with denominator \(100\): \(\frac{2}{5} = \frac{40}{100} = 40\%\). 2. For b), write the percent as a fraction and simplify: \(18\% = \frac{18}{100} = \frac{9}{50}\). The missing number is \(9\). 3. For c), write the fraction with denominator \(100\): \(\frac{7}{20} = \frac{35}{100} = 35\%\). 4. For d), write the percent as a fraction and simplify: \(88\% = \frac{88}{100} = \frac{22}{25}\). The missing number is \(22\).

Answer

a) \(40\%\) b) \(9\) c) \(35\%\) d) \(22\)
5114556
Write each value as a percent: a) \(\frac{3}{10}\) b) \(0.15\) c) \(\frac{11}{50}\) d) \(0.085\) e) \(\frac{1}{4}\)

Hints

- What does “percent” mean? - Can you write each fraction with denominator \(100\)? - What happens to the decimal point when you multiply a decimal by \(100\)?

Solution

1. \(\frac{3}{10} = \frac{30}{100} = 30\%\). 2. \(0.15 = \frac{15}{100} = 15\%\). 3. \(\frac{11}{50} = \frac{22}{100} = 22\%\). 4. \(0.085 \times 100 = 8.5\), so \(0.085 = 8.5\%\). 5. \(\frac{1}{4} = \frac{25}{100} = 25\%\).

Answer

a) \(30\%\) b) \(15\%\) c) \(22\%\) d) \(8.5\%\) e) \(25\%\)
5114646
A fruit drink is \(\frac{7}{20}\) apple juice and \(\frac{11}{50}\) cherry juice. The rest is water. a) Write the amount of each fruit juice as a percent. b) Is more than half of the drink fruit juice? Explain using percents.

Hints

- What percent represents one half? - Can you write each fraction with denominator \(100\)? - Add the two fruit-juice percents.

Solution

1. Apple juice: \(\frac{7}{20} = \frac{35}{100} = 35\%\). 2. Cherry juice: \(\frac{11}{50} = \frac{22}{100} = 22\%\). 3. Add the fruit-juice portions: \(35\% + 22\% = 57\%\). 4. Since half is \(50\%\) and \(57\% > 50\%\), more than half of the drink is fruit juice.

Answer

a) Apple juice: \(35\%\); cherry juice: \(22\%\) b) Yes. The total fruit-juice portion is \(57\%\), which is greater than \(50\%\).
5114676
Write each value as a percent. a) \(\frac{7}{25}\) b) \(\frac{13}{200}\) c) \(0.045\) d) \(1\frac{2}{5}\) e) \(\frac{3}{8}\)

Hints

- Can you write each fraction with denominator \(100\)? - How many places does the decimal point move when you convert a decimal to a percent? - What does “percent” mean?

Solution

1. For a), \(\frac{7}{25} = \frac{28}{100} = 28\%\). 2. For b), \(\frac{13}{200} = 0.065 = 6.5\%\). 3. For c), \(0.045 \times 100 = 4.5\), so \(0.045 = 4.5\%\). 4. For d), \(1\frac{2}{5} = 1.4 = 140\%\). 5. For e), \(3 \div 8 = 0.375\), so \(\frac{3}{8} = 37.5\%\).

Answer

a) \(28\%\) b) \(6.5\%\) c) \(4.5\%\) d) \(140\%\) e) \(37.5\%\)
5114706
Sixth-grade students at a school choose among several clubs. The portions of students in four clubs are: - Soccer: \(\frac{1}{4}\) - Choir: \(\frac{3}{20}\) - Drama: \(\frac{2}{25}\) - Woodworking: \(\frac{7}{50}\) Write each portion as a percent. Which of these clubs is the most popular?

Hints

- Can you write each fraction with denominator \(100\)? - What does “percent” mean? - Once the denominators are the same, which numerator is greatest?

Solution

1. Soccer: \(\frac{1}{4} = \frac{25}{100} = 25\%\). 2. Choir: \(\frac{3}{20} = \frac{15}{100} = 15\%\). 3. Drama: \(\frac{2}{25} = \frac{8}{100} = 8\%\). 4. Woodworking: \(\frac{7}{50} = \frac{14}{100} = 14\%\). 5. Since \(25\% > 15\% > 14\% > 8\%\), soccer is the most popular of the four clubs.

Answer

Soccer: \(25\%\); choir: \(15\%\); drama: \(8\%\); woodworking: \(14\%\). Soccer is the most popular of these clubs.
5114736
A class is planning a buffet for a school event. Of the foods, \(45\%\) are vegetarian but not vegan, and \(35\%\) contain meat. All the remaining foods are vegan. What percent of the foods are vegan?

Hints

- What does \(100\%\) represent in this situation? - What percent of the foods is already accounted for? - How can you find the remaining percent?

Solution

1. Add the two nonvegan portions: \(45\% + 35\% = 80\%\). 2. Subtract from the whole: \(100\% - 80\% = 20\%\).

Answer

\(20\%\) of the foods are vegan.
5114756
A square grid has \(10 \times 10\) small squares. - \(0.3\) of the squares are blue. - \(\frac{15}{100}\) of the squares are red. - \(20\%\) of the squares are yellow. The remaining squares are white. How many squares are white? Also write the white portion as a fraction in simplest form.

Hints

- How many squares are in the grid altogether? - Convert each decimal, fraction, or percent to a number of squares. - How do you simplify the fraction for the white squares?

Solution

1. The grid has \(10 \times 10 = 100\) squares. 2. Blue squares: \(0.3 = 30\%\), so \(30\) squares are blue. 3. Red squares: \(\frac{15}{100}\) of \(100\) is \(15\) squares. 4. Yellow squares: \(20\%\) of \(100\) is \(20\) squares. 5. The total number of colored squares is \(30 + 15 + 20 = 65\). 6. The number of white squares is \(100 - 65 = 35\). The white portion is \(\frac{35}{100} = \frac{7}{20}\).

Answer

\(35\) squares are white. The white portion is \(\frac{7}{20}\).
5114856
Copy and complete the table. <table> <tr> <th>Fraction</th> <th>Decimal</th> <th>Percent</th> </tr> <tr> <td>\(\frac{2}{5}\)</td> <td></td> <td></td> </tr> <tr> <td></td> <td>\(0.08\)</td> <td></td> </tr> <tr> <td></td> <td></td> <td>\(15\%\)</td> </tr> <tr> <td></td> <td>\(0.004\)</td> <td></td> </tr> </table>

Hints

- Percent means “per hundred.” - Multiply a decimal by \(100\) to write it as a percent. - Rewrite a fraction with a denominator of \(100\) when that is convenient.

Solution

1. \(\frac{2}{5} = 0.4 = 40\%\). 2. \(0.08 = \frac{8}{100} = \frac{2}{25} = 8\%\). 3. \(15\% = 0.15 = \frac{15}{100} = \frac{3}{20}\). 4. \(0.004 = \frac{4}{1000} = \frac{1}{250} = 0.4\%\).

Answer

Row 1: \(0.4\); \(40\%\) Row 2: \(\frac{2}{25}\); \(8\%\) Row 3: \(\frac{3}{20}\); \(0.15\) Row 4: \(\frac{1}{250}\); \(0.4\%\)
5114956
Write each fraction or decimal as a percent. Round to the nearest tenth of a percent. a) \(\frac{4}{9}\) b) \(0.0725\) c) \(\frac{11}{13}\) d) \(0.009\)

Hints

- For a fraction, divide the numerator by the denominator. - How many places does the decimal point move when you convert to a percent? - Use the hundredths digit of the percent to decide how to round.

Solution

1. For a), \(4 \div 9 = 0.444\ldots\), so \(\frac{4}{9} = 44.444\ldots\% \approx 44.4\%\). 2. For b), \(0.0725 \times 100 = 7.25\), so \(0.0725 = 7.25\% \approx 7.3\%\). 3. For c), \(11 \div 13 = 0.846153\ldots\), so \(\frac{11}{13} = 84.6153\ldots\% \approx 84.6\%\). 4. For d), \(0.009 \times 100 = 0.9\), so \(0.009 = 0.9\%\).

Answer

a) \(44.4\%\) b) \(7.3\%\) c) \(84.6\%\) d) \(0.9\%\)
5115096
A circle graph is divided into five equal sectors. a) Find the central angle and the percent of the whole represented by one sector. b) One sector is divided into two equal parts to create a new category. Find the central angle and percent represented by each of the two smaller sectors.

Hints

- A full circle measures \(360^\circ\). - Five equal sectors divide both \(360^\circ\) and \(100\%\) equally. - Dividing one sector in half also divides its angle and percent in half.

Solution

1. One of five equal sectors has central angle \(360^\circ\div5=72^\circ\). 2. One sector represents \(100\%\div5=20\%\) of the whole. 3. Each half of that sector has central angle \(72^\circ\div2=36^\circ\). 4. Each smaller sector represents \(20\%\div2=10\%\) of the whole.

Answer

a) \(72^\circ\) and \(20\%\) b) Each smaller sector is \(36^\circ\) and represents \(10\%\).
5115246
For each situation, decide whether the unknown is the whole, the part, or the percent. Then calculate the answer. a) What is \(15\%\) of \(400\,\text{m}\)? b) What percent of \(60\) apples is \(12\) apples? c) An amount equal to \(10\%\) of an original price is \(\$5\). What was the original price?

Hints

- First identify the whole, the part, and the percent in each situation. - Can you rewrite each situation in the form “\(p\%\) of the whole is the part”? - For b), write the part-to-whole ratio as a fraction and find an equivalent fraction with denominator \(100\). - For c), you know the amount represented by \(10\%\). How many groups of \(10\%\) make \(100\%\)?

Solution

1. In part a), the part is unknown. Compute \(400\,\text{m} \times 0.15 = 60\,\text{m}\). 2. In part b), the percent is unknown. Compute \(\frac{12}{60} = \frac{1}{5} = \frac{20}{100} = 20\%\). 3. In part c), the whole is unknown. Compute \(\$5 \div 0.10 = \$50\).

Answer

a) Part; \(60\,\text{m}\) b) Percent; \(20\%\) c) Whole; \(\$50\)
5115276
During a bicycle ride, a group has traveled \(12\,\text{km}\). This is \(40\%\) of the planned route. Identify the quantity that represents the whole, find the total route length, and check your answer.

Hints

- Decide what quantity represents \(100\%\). - Use the known part and its percent to find the whole. - Check by finding \(40\%\) of your result.

Solution

1. The whole is the total planned route. 2. Since \(12\,\text{km}\) is \(40\%\) of the route, the total is \(12\,\text{km} \div 0.40 = 30\,\text{km}\). 3. Check: \(30\,\text{km} \times 0.40 = 12\,\text{km}\), which matches the given distance.

Answer

The whole is the total planned route, and its length is \(30\,\text{km}\). The check gives \(30\,\text{km} \times 0.40 = 12\,\text{km}\).
5115336
Write each portion as a percent. a) One out of every two raffle tickets is a winner. b) Three out of four students surveyed own a smartphone. c) A geography model shows that one fifth of a region is desert.

Hints

- First write each described portion as a fraction. - What does “percent” mean? - How can you write each fraction with denominator \(100\)?

Solution

1. “One out of every two” means \(\frac{1}{2}\): \(\frac{1}{2} = \frac{50}{100} = 50\%\). 2. “Three out of four” means \(\frac{3}{4}\): \(\frac{3}{4} = \frac{75}{100} = 75\%\). 3. “One fifth” means \(\frac{1}{5}\): \(\frac{1}{5} = \frac{20}{100} = 20\%\).

Answer

a) \(50\%\) b) \(75\%\) c) \(20\%\)
5115396
Find the whole, \(G\), in each equation. a) \(10\% \times G = 7\) b) \(50\% \times G = 18\) c) \(25\% \times G = 11\) d) \(100\% \times G = 34\)

Hints

- Write each percent as a decimal or fraction. - Divide the part by that decimal to find the whole. - What does \(100\%\) mean for the relationship between the part and the whole?

Solution

1. Divide each given part by the percent written as a decimal. 2. a) \(G = 7 \div 0.10 = 70\) 3. b) \(G = 18 \div 0.50 = 36\) 4. c) \(G = 11 \div 0.25 = 44\) 5. d) \(G = 34 \div 1 = 34\)

Answer

a) \(G = 70\) b) \(G = 36\) c) \(G = 44\) d) \(G = 34\)
5115636
A school festival booth sold part of its inventory. Find the original number of each item. a) \(12\) bracelets were \(15\%\) of the inventory. b) \(45\) key chains were \(60\%\) of the inventory. c) \(21\) postcards were \(30\%\) of the inventory.

Hints

- Find how many items correspond to \(1\%\), or divide by the percent written as a decimal. - The original inventory represents \(100\%\).

Solution

1. a) \(12 \div 0.15 = 80\) bracelets 2. b) \(45 \div 0.60 = 75\) key chains 3. c) \(21 \div 0.30 = 70\) postcards

Answer

a) \(80\) bracelets b) \(75\) key chains c) \(70\) postcards
5115656
Find the whole, \(G\), using a method of your choice. a) \(12\%\) of \(G\) is \(42\). b) \(35\%\) of \(G\) is \(105\). c) \(80\%\) of \(G\) is \(144\). d) \(150\%\) of \(G\) is \(330\).

Hints

- You may first find \(1\%\), or divide the part by the percent written as a decimal. - For part d), decide whether the whole should be greater or less than \(330\) when \(330\) represents \(150\%\).

Solution

1. a) \(G = 42 \div 0.12 = 350\) 2. b) \(G = 105 \div 0.35 = 300\) 3. c) \(G = 144 \div 0.80 = 180\) 4. d) \(G = 330 \div 1.50 = 220\)

Answer

a) \(G = 350\) b) \(G = 300\) c) \(G = 180\) d) \(G = 220\)
5116036
A class was surveyed about favorite drinks. One fourth of the students chose apple juice, \(0.3\) of the students chose water, \(35\%\) chose iced tea, and the rest chose lemonade. a) Write the portions for apple juice and water as percents. b) What percent of the class chose lemonade?

Hints

- What percent represents the whole class? - First write all the given portions as percents. - Subtract the known total from the whole.

Solution

1. Convert the known portions: \(\frac{1}{4} = 25\%\) for apple juice, and \(0.3 = 30\%\) for water. 2. Add the known percents: \(25\% + 30\% + 35\% = 90\%\). 3. Subtract from the whole: \(100\% - 90\% = 10\%\).

Answer

a) Apple juice: \(25\%\); water: \(30\%\) b) \(10\%\) of the class chose lemonade.
5116056
Which fractions can be written as whole-number percents? Find the percent for each fraction that can. For the others, briefly explain why the percent is not a whole number. a) \(\frac{3}{5}\) b) \(\frac{5}{8}\) c) \(\frac{9}{20}\) d) \(\frac{7}{30}\)

Hints

- Try to write each fraction with denominator \(100\). - What must be true of the denominator for the fraction to become an exact number of hundredths? - You can multiply the numerator by \(100\), then divide by the denominator.

Solution

1. A fraction is a whole-number percent when \(100\) times its numerator is divisible by its denominator. 2. For a), \(\frac{3}{5} \times 100 = 60\), so \(\frac{3}{5} = 60\%\). 3. For b), \(\frac{5}{8} \times 100 = \frac{500}{8} = 62.5\), so the percent is not a whole number. 4. For c), \(\frac{9}{20} \times 100 = 45\), so \(\frac{9}{20} = 45\%\). 5. For d), \(\frac{7}{30} \times 100 = \frac{70}{3} = 23.333\ldots\), so the percent is not a whole number.

Answer

Whole-number percents: a) \(\frac{3}{5} = 60\%\) c) \(\frac{9}{20} = 45\%\) Not whole-number percents: b) \(\frac{5}{8} = 62.5\%\), because \(500\) is not divisible by \(8\) d) \(\frac{7}{30} = 23.333\ldots\%\), because \(700\) is not divisible by \(30\)
5116086
Complete the percent table. Calculate each missing value. <table> <tr><th>Whole</th><th>Percent</th><th>Part</th></tr> <tr><td>\(\$450\)</td><td>\(12\%\)</td><td>?</td></tr> <tr><td>\(80\,\text{kg}\)</td><td>?</td><td>\(20\,\text{kg}\)</td></tr> <tr><td>?</td><td>\(5\%\)</td><td>\(15\,\text{m}\)</td></tr> </table>

Hints

- First decide whether each missing value is the whole, the percent, or the part. - Use the relationship: part \(=\) percent written as a decimal \(\times\) whole. - You can write the percent as a decimal or as a fraction to make the calculation easier.

Solution

1. The missing part is \(\$450 \times 0.12 = \$54\). 2. The missing percent is \(\frac{20\,\text{kg}}{80\,\text{kg}} = 0.25 = 25\%\). 3. The missing whole is \(15\,\text{m} \div 0.05 = 300\,\text{m}\).

Answer

1. \(\$54\) 2. \(25\%\) 3. \(300\,\text{m}\)
5116106
After a long ride, an e-bike battery has \(35\%\) of its energy remaining. The remaining energy is \(210\,\text{Wh}\). How much energy can the battery store when fully charged?

Hints

- The full battery represents \(100\%\). - Use \(210\,\text{Wh}\) and \(35\%\) to find the whole capacity.

Solution

1. The \(210\,\text{Wh}\) represents \(35\%\) of the full capacity. 2. Divide by the percent written as a decimal: \(210\,\text{Wh} \div 0.35 = 600\,\text{Wh}\).

Answer

The battery’s full capacity is \(600\,\text{Wh}\).
5117436
A bag of trail mix contains \(120\,\text{g}\) of hazelnuts. The label says that hazelnuts make up \(20\%\) of the bag’s contents. What is the total mass of the trail mix?

Hints

- Decide which quantity is the part and which is the whole. - How many groups of \(20\%\) make \(100\%\)?

Solution

1. The \(120\,\text{g}\) of hazelnuts represents \(20\%\) of the total. 2. Find the whole: \(120\,\text{g} \div 0.20 = 600\,\text{g}\).

Answer

The trail mix has a total mass of \(600\,\text{g}\).
5117766
A class was surveyed about favorite sports. Write each portion as a decimal and a percent. 1. Soccer: \(\frac{2}{5}\) 2. Swimming: \(\frac{3}{20}\) 3. Basketball: \(\frac{1}{4}\) 4. Gymnastics: \(\frac{1}{10}\)

Hints

- Can you write each fraction with denominator \(10\), \(100\), or \(1000\)? - What does “percent” mean? - How does the decimal point move when you multiply a decimal by \(100\)?

Solution

1. Soccer: \(\frac{2}{5} = 0.4 = 40\%\). 2. Swimming: \(\frac{3}{20} = 0.15 = 15\%\). 3. Basketball: \(\frac{1}{4} = 0.25 = 25\%\). 4. Gymnastics: \(\frac{1}{10} = 0.1 = 10\%\).

Answer

1. \(0.4 = 40\%\) 2. \(0.15 = 15\%\) 3. \(0.25 = 25\%\) 4. \(0.1 = 10\%\)
5118116
Find the value of the sum and write the result as a percent: \(\frac{3}{10} + 12\% + 0.13\)

Hints

- Write every term in the same form. - How many hundredths are in three tenths? - Why is the sum easier to find when all terms are percents?

Solution

1. Convert \(\frac{3}{10}\) to a percent: \(\frac{3}{10} = \frac{30}{100} = 30\%\). 2. Convert \(0.13\) to a percent: \(0.13 = 13\%\). 3. Add the three percent values: \(30\% + 12\% + 13\% = 55\%\).

Answer

\(55\%\)
5128496
A class of \(25\) students was surveyed using three response choices about sports outside school. - \(15\) students chose soccer. - \(6\) students chose tennis. - The rest chose “I do not play a sport outside school.” a) Write the fraction of students who chose soccer as a fraction in simplest form and as a percent. b) Write the fraction of students who chose tennis as a decimal and as a percent. c) What percent of the class chose “I do not play a sport outside school”?

Hints

- Write each part as the number in the group divided by the total number of students. - Since \(25 \times 4 = 100\), fractions with denominator \(25\) can be rewritten with denominator \(100\). - The percentages for all three groups must add to \(100\%\).

Solution

1. For soccer, the fraction is \(\frac{15}{25} = \frac{3}{5}\). Since \(\frac{3}{5} = \frac{60}{100}\), the percent is \(60\%\). 2. For tennis, the fraction is \(\frac{6}{25}\). Dividing gives \(6 \div 25 = 0.24\), so the percent is \(24\%\). 3. The number who do not play a sport is \(25 - 15 - 6 = 4\). The fraction is \(\frac{4}{25} = \frac{16}{100}\), so the percent is \(16\%\).

Answer

a) \(\frac{3}{5}\) and \(60\%\) b) \(0.24\) and \(24\%\) c) \(16\%\)
5139396
The list shows several ways to represent quantities. Which values are equivalent? Group the values that represent the same quantity. \(\frac{3}{4}\); \(0.75\); \(7.5\%\); \(75\%\); \(\frac{75}{10}\); \(\frac{6}{8}\)

Hints

- Rewrite every value in the same form, such as all decimals or all percents. - To convert a fraction to a decimal, divide the numerator by the denominator. - A percent means a number out of \(100\). - Simplifying fractions may make equivalent values easier to recognize.

Solution

1. Rewrite each value as a decimal or percent: \(\frac{3}{4} = 0.75 = 75\%\) \(0.75 = 75\%\) \(7.5\% = 0.075\) \(75\% = 0.75\) \(\frac{75}{10} = 7.5 = 750\%\) \(\frac{6}{8} = \frac{3}{4} = 0.75 = 75\%\) 2. Therefore, \(\frac{3}{4}\), \(0.75\), \(75\%\), and \(\frac{6}{8}\) are equivalent. 3. The values \(7.5\%\) and \(\frac{75}{10}\) are not equivalent to any other value in the list.

Answer

Equivalent group: \(\frac{3}{4}\), \(0.75\), \(75\%\), and \(\frac{6}{8}\). The values \(7.5\%\) and \(\frac{75}{10}\) each form a group by themselves.
5319276
A school surveyed sixth-grade students about their favorite sport. The circle graph shows the results. Exactly \(45\) students chose gymnastics. How many students participated in the survey?
Figure for problem 531927

Hints

- Read the gymnastics percent from the graph. - Use that known part to find \(100\%\) of the survey group.

Solution

1. Gymnastics represents \(15\%\) of the survey responses. 2. Since \(45\) is \(15\%\) of the group, the total is \(45 \div 0.15 = 300\) students.

Answer

\(300\) students participated in the survey.
5320186
The square grid shown has \(100\) equal small squares. a) What percent of the grid is shaded orange? b) Write the shaded portion as a fraction in simplest form.
Figure for problem 532018

Hints

- Count the total number of small squares. - Count the shaded squares. - A percent describes a portion out of \(100\). - First write the portion as a fraction with denominator \(100\). - Simplify the fraction completely.

Solution

1. The grid has \(10\) rows and \(10\) columns, so it contains \(10 \times 10 = 100\) small squares. 2. Count the shaded squares: \(28\) squares are orange. 3. Since \(28\) out of \(100\) squares are shaded, the shaded portion is \(28\%\). 4. As a fraction, the shaded portion is \(\frac{28}{100}\). Divide the numerator and denominator by \(4\): \(\frac{28}{100} = \frac{7}{25}\).

Answer

a) \(28\%\) b) \(\frac{7}{25}\)
5320856
Look at the grid. a) What portion of the total area is shaded blue? Write the portion as a fraction in simplest form, a decimal, and a percent. b) What portion of the total area is unshaded? Write this portion as a fraction in simplest form, a decimal, and a percent.
Figure for problem 532085

Hints

- Count the total number of small squares. - Count the blue squares and write the portion as a fraction. - Simplify the fraction, then convert it to a decimal and a percent. - The shaded and unshaded portions must add to \(1\), or \(100\%\).

Solution

1. The grid has \(4 \times 5 = 20\) squares. 2. Count the shaded squares: \(8\) squares are blue. 3. The shaded portion is \(\frac{8}{20} = \frac{2}{5} = 0.4 = 40\%\). 4. There are \(20 - 8 = 12\) unshaded squares. The unshaded portion is \(\frac{12}{20} = \frac{3}{5} = 0.6 = 60\%\).

Answer

a) Shaded portion: \(\frac{2}{5}\), \(0.4\), \(40\%\) b) Unshaded portion: \(\frac{3}{5}\), \(0.6\), \(60\%\)
5355106
A square mosaic is made of \(25\) equal tiles. Some tiles are shaded gray, as shown. What fraction of the mosaic is gray? Also write the portion as a percent.
Figure for problem 535510

Hints

- Count all the small tiles. - Count the gray tiles. - How can you write a fraction with denominator \(25\) as a fraction with denominator \(100\)? - Percent means “per hundred.”

Solution

1. The grid has \(5 \times 5 = 25\) tiles. 2. Count the gray tiles: \(6\) tiles are gray. 3. The gray portion is \(\frac{6}{25}\). 4. Multiply the numerator and denominator by \(4\): \(\frac{6}{25} = \frac{24}{100} = 24\%\).

Answer

The gray portion is \(\frac{6}{25}\), which is \(24\%\).
5355196
The circle graph shows how a student spends time during the afternoon. a) Which activity represents exactly \(25\%\) of the time? b) Explain why this portion is especially easy to recognize in a circle graph.
Figure for problem 535519

Hints

- Write \(25\%\) as a simple fraction. - Look for a sector that is one fourth of the circle. - What familiar angle measures one fourth of a full turn?

Solution

1. A portion of \(25\%\) is one fourth of a circle. The Homework sector represents \(25\%\). 2. One fourth of a circle has a central angle of \(90^\circ\). This right-angle sector is easy to recognize.

Answer

a) Homework represents \(25\%\). b) A portion of \(25\%\) is one fourth of a circle, which has a central angle of \(90^\circ\). This forms a right-angle sector.
5355586
A pizza was cut into \(10\) equal slices. The shaded slices have already been eaten. a) What fraction of the pizza remains unshaded? b) What percent of the pizza has been eaten?
Figure for problem 535558

Hints

- Notice whether each part asks about what remains or what was eaten. - How can you change a denominator of \(10\) to \(100\)?

Solution

1. There are \(10\) slices in all. Since \(3\) are shaded, \(10 - 3 = 7\) slices remain. The remaining portion is \(\frac{7}{10}\). 2. The eaten portion is \(\frac{3}{10}\). 3. Convert to a percent: \(\frac{3}{10} = \frac{30}{100} = 30\%\).

Answer

a) \(\frac{7}{10}\) of the pizza remains. b) \(30\%\) of the pizza has been eaten.
5355886
A parking garage has \(100\) spaces arranged in a rectangular grid. The occupied spaces are shaded in the figure. What percent of the spaces are still available?
Figure for problem 535588

Hints

- How many spaces are there altogether? - How many shaded spaces are occupied? - How many unshaded spaces remain? - Percent means “per hundred.”

Solution

1. There are \(100\) parking spaces altogether. 2. The figure shows \(35\) shaded, occupied spaces. 3. The number of available spaces is \(100 - 35 = 65\). 4. Since there are \(100\) spaces in all, \(65\) available spaces represent \(65\%\).

Answer

\(65\%\) of the parking spaces are available.
5357496
A parking lot is partly occupied. The strip represents all the parking spaces. What percent of the spaces are occupied, shown by the shaded portion, and what percent are available, shown by the unshaded portion?
Figure for problem 535749

Hints

- Find the shaded portion of the whole strip. - The whole represents \(100\%\).

Solution

1. The strip has \(10\) equal parts. 2. Nine parts are shaded, so the occupied portion is \(\frac{9}{10} = 90\%\). 3. The remaining portion is \(100\% - 90\% = 10\%\).

Answer

Occupied: \(90\%\) Available: \(10\%\)
5358236
For each figure, find the percent of the total area that is shaded.
Figure for problem 535823

Hints

- Count the total number of small squares in each grid. - Count the shaded squares. - Write each fraction with denominator \(100\).

Solution

1. In figure a), the grid has \(4 \times 5 = 20\) equal squares. Nine are shaded, so the shaded portion is \(\frac{9}{20} = \frac{45}{100} = 45\%\). 2. In figure b), the grid has \(2 \times 5 = 10\) equal squares. Three are shaded, so the shaded portion is \(\frac{3}{10} = \frac{30}{100} = 30\%\).

Answer

a) \(45\%\) b) \(30\%\)
5102126
Complete the table so that each row shows the same value in three different forms. Write each fraction in simplest form. <table> <tr> <th>Percent</th> <th>Fraction (simplest form)</th> <th>Decimal</th> </tr> <tr> <td>\(35\%\)</td> <td>…</td> <td>…</td> </tr> <tr> <td>…</td> <td>\(\frac{4}{5}\)</td> <td>…</td> </tr> <tr> <td>…</td> <td>…</td> <td>\(0.12\)</td> </tr> </table>

Hints

- How are fractions with denominator \(100\) related to decimals? - Can you write a fraction as an equivalent fraction with denominator \(100\)? - What happens to the decimal point when you convert a decimal to a percent?

Solution

1. First row: \(35\% = \frac{35}{100} = \frac{7}{20}\). As a decimal, \(35 \div 100 = 0.35\). 2. Second row: \(\frac{4}{5} = \frac{80}{100} = 80\%\). As a decimal, \(4 \div 5 = 0.8\). 3. Third row: \(0.12 = \frac{12}{100} = \frac{3}{25}\). As a percent, \(0.12 \times 100 = 12\%\).

Answer

First row: \(\frac{7}{20}\) and \(0.35\) Second row: \(80\%\) and \(0.8\) Third row: \(12\%\) and \(\frac{3}{25}\)
5102246
Find each missing number so that the equations are true: a) \(\frac{\Box}{40} = 15\%\) b) \(\frac{12}{\Box} = 40\%\) c) \(\frac{21}{70} = \frac{\Box}{100} = \ldots\%\)

Hints

- Can you write each percent as a fraction in simplest form? - Remember that a fraction bar also represents division. - What happens when you first write the percent as a fraction with denominator \(100\)?

Solution

1. For a), write \(15\%\) as a fraction and simplify: \(15\% = \frac{15}{100} = \frac{3}{20}\). Multiply the numerator and denominator by \(2\): \(\frac{3}{20} = \frac{6}{40}\). Therefore, the missing numerator is \(6\). 2. For b), write \(40\%\) as \(\frac{2}{5}\). Since \(\frac{12}{x} = \frac{2}{5}\), multiplying \(\frac{2}{5}\) by \(\frac{6}{6}\) gives \(\frac{12}{30}\), so \(x = 30\). 3. For c), simplify \(\frac{21}{70}\) to \(\frac{3}{10}\), then write it with denominator \(100\): \(\frac{3}{10} = \frac{30}{100} = 30\%\).

Answer

a) \(6\) b) \(30\) c) \(30\) and \(30\%\)
5102256
Three values represent portions of a whole: \(A=\frac{14}{25}\), \(B=0.49\), and \(C=\frac{123}{250}\). Which value is closest to one-half, or \(50\%\)? Convert all three values to percentages and justify your answer.

Hints

- Convert each value to a percent. - Find how far each percent is from \(50\%\). - The value with the smallest distance is closest to one-half.

Solution

1. Convert \(A\): \(\frac{14}{25}=\frac{56}{100}=56\%\). 2. Convert \(B\): \(0.49=49\%\). 3. Convert \(C\): \(\frac{123}{250}=0.492=49.2\%\). 4. The distances from \(50\%\) are \(6\) percentage points for \(A\), \(1\) percentage point for \(B\), and \(0.8\) percentage point for \(C\). 5. The smallest distance is \(0.8\) percentage point, so \(C\) is closest to one-half.

Answer

\(C=\frac{123}{250}\), because \(A=56\%\), \(B=49\%\), and \(C=49.2\%\), which is only \(0.8\) percentage point from \(50\%\).
5102366
A student converted each fraction to a percent. Check the student's work. Correct any error by first simplifying the fraction completely and then finding the correct percent. 1. \(\frac{14}{35} = 40\%\) 2. \(\frac{27}{45} = 50\%\) 3. \(\frac{66}{110} = 60\%\)

Hints

- Work each conversion yourself before checking the stated result. - What common factor can you divide from each numerator and denominator? - Once a fraction has denominator \(100\), you can read the percent directly.

Solution

1. For \(\frac{14}{35}\), divide the numerator and denominator by their greatest common factor, \(7\): \(\frac{14}{35} = \frac{2}{5} = \frac{40}{100} = 40\%\). The result is correct. 2. For \(\frac{27}{45}\), divide the numerator and denominator by their greatest common factor, \(9\): \(\frac{27}{45} = \frac{3}{5} = \frac{60}{100} = 60\%\). The stated result, \(50\%\), is incorrect. 3. For \(\frac{66}{110}\), divide the numerator and denominator by their greatest common factor, \(22\): \(\frac{66}{110} = \frac{3}{5} = \frac{60}{100} = 60\%\). The result is correct.

Answer

1. Correct: \(\frac{14}{35} = \frac{2}{5} = 40\%\) 2. Incorrect: \(\frac{27}{45} = \frac{3}{5} = 60\%\), not \(50\%\) 3. Correct: \(\frac{66}{110} = \frac{3}{5} = 60\%\)
5102376
Find the missing value \(x\) that makes each statement true. Simplify any fractions when that makes the work easier. a) \(\frac{x}{125} = 20\%\) b) \(\frac{36}{x} = 75\%\) c) \(\frac{21}{28} = x\%\)

Hints

- Write each percent as a fraction in simplest form. - Can you rearrange each equation so that \(x\) is by itself? - For c), simplify the fraction before converting it to a percent.

Solution

1. For a), \(20\% = \frac{20}{100} = \frac{1}{5}\). Solve \(\frac{x}{125} = \frac{1}{5}\): \(x = 125 \times \frac{1}{5} = 25\). 2. For b), \(75\% = \frac{75}{100} = \frac{3}{4}\). Solve \(\frac{36}{x} = \frac{3}{4}\): \(3x = 36 \times 4 = 144\), so \(x = 144 \div 3 = 48\). 3. For c), simplify \(\frac{21}{28}\) by dividing by \(7\): \(\frac{21}{28} = \frac{3}{4} = 0.75 = 75\%\). Therefore, \(x = 75\).

Answer

a) \(x = 25\) b) \(x = 48\) c) \(x = 75\)
5104026
Three students discuss the value \(125\%\). Decide whether each statement is correct. If a statement is incorrect, correct it and explain why. Maya says, “Because it is a percent, the value must be less than \(1\).” Ben says, “Written as a decimal, \(125\%\) is exactly \(1.25\).” Carlos says, “Written as a fraction in simplest form, \(125\%\) is \(\frac{5}{4}\).”

Hints

- Can a percent describe more than one whole? - How do you convert any percent to a decimal? - First write the percent as a fraction with denominator \(100\), then simplify.

Solution

1. Maya's statement is incorrect. Percents can be greater than \(100\%\), which represent values greater than \(1\). Since \(125\% = 1.25\), this value is greater than \(1\). 2. Ben's statement is correct. Divide by \(100\) to convert a percent to a decimal: \(125 \div 100 = 1.25\). 3. Carlos's statement is correct. Write \(125\%\) as \(\frac{125}{100}\), then divide the numerator and denominator by \(25\): \(\frac{125}{100} = \frac{5}{4}\).

Answer

Maya is incorrect: \(125\% = 1.25\), which is greater than \(1\). Ben is correct: \(125\% = 1.25\). Carlos is correct: \(125\% = \frac{125}{100} = \frac{5}{4}\).
5104076
Compare each pair. Write \(<\), \(>\), or \(=\). Convert each fraction to a percent first. a) \(\frac{3}{8}\) and \(40\%\) b) \(\frac{12}{60}\) and \(20\%\) c) \(\frac{9}{12}\) and \(70\%\) d) \(\frac{1}{3}\) and \(33\%\)

Hints

- Write both values in each pair in the same form. - Some fractions can be simplified before you write them with denominator \(100\). - When an equivalent fraction with denominator \(100\) is not convenient, divide the numerator by the denominator.

Solution

1. For a), \(3 \div 8 = 0.375 = 37.5\%\). Since \(37.5\% < 40\%\), \(\frac{3}{8} < 40\%\). 2. For b), simplify \(\frac{12}{60}\) to \(\frac{1}{5}\), then write \(\frac{1}{5} = \frac{20}{100} = 20\%\). Therefore, \(\frac{12}{60} = 20\%\). 3. For c), simplify \(\frac{9}{12}\) to \(\frac{3}{4}\), then write \(\frac{3}{4} = \frac{75}{100} = 75\%\). Since \(75\% > 70\%\), \(\frac{9}{12} > 70\%\). 4. For d), \(1 \div 3 = 0.333\ldots\), so \(\frac{1}{3} = 33.333\ldots\%\). Since \(33.333\ldots\% > 33\%\), \(\frac{1}{3} > 33\%\).

Answer

a) \(<\) b) \(=\) c) \(>\) d) \(>\)
5107216
Maya wants to buy a tablet. She has saved \(30\%\) of its price, and her parents will contribute one half of its price. Her grandfather gives her \(\$100\), which is exactly one fourth of the tablet’s price. a) Find the price of the tablet. b) Determine whether the money is enough to buy both the tablet and a screen protector that costs \(\$14.50\). Explain your answer.

Hints

- Use the grandfather’s gift to find the full price. - Express one half as a fraction or percent. - Add all three contributions, then compare the amount left after the tablet purchase with \(\$14.50\).

Solution

1. The \(\$100\) gift is \(25\%\) of the tablet’s price. Scaling from \(25\%\) to \(100\%\), the price is \(\$100 \times 4 = \$400\). 2. Maya has saved \(30\%\) of \(\$400\): \(\$400 \times 0.30 = \$120\). 3. Her parents contribute one half of \(\$400\), which is \(\$200\). 4. The total available is \(\$120 + \$200 + \$100 = \$420\). 5. After buying the tablet, \(\$420 - \$400 = \$20\) remains. Because \(\$20 > \$14.50\), the remaining money is enough for the screen protector.

Answer

a) \(\$400\) b) Yes. Maya has \(\$420\) in all, so \(\$20\) remains after buying the tablet. That is more than the \(\$14.50\) cost of the screen protector.
5109636
Lena is saving for a new smartphone. Her grandparents gave her one fourth of its price. She earned another \(35\%\) of the price by doing yard work. Her parents will give her the remaining \(\$140\). What is the full price of the smartphone?

Hints

- Convert one fourth to a percent. - Find the percent of the price represented by the remaining \(\$140\). - Scale from that part to \(100\%\).

Solution

1. One fourth is \(25\%\). 2. The first two amounts represent \(25\% + 35\% = 60\%\) of the price. 3. The remaining \(\$140\) represents \(100\% - 60\% = 40\%\) of the price. 4. Find the whole: \(\$140 \div 0.40 = \$350\).

Answer

The smartphone costs \(\$350\).
5109646
A school is planning the budget for a class trip. Lodging will use \(45\%\) of the total cost, and meals will use one fifth. The remaining \(\$630\) will pay for transportation and admission fees. Find the total cost of the trip.

Hints

- Convert one fifth to a percent. - Find the percent left after lodging and meals. - Set the remaining percent equal to \(\$630\), then find \(100\%\).

Solution

1. One fifth is \(20\%\). 2. Lodging and meals use \(45\% + 20\% = 65\%\) of the budget. 3. Transportation and admission fees use \(100\% - 65\% = 35\%\). 4. Since \(35\%\) is \(\$630\), the whole budget is \(\$630 \div 0.35 = \$1800\).

Answer

The total cost is \(\$1800\).
5114166
A rectangular flower bed has an area of \(12.6\,\text{m}^2\). This is \(14\%\) of the area of a rectangular garden. a) Find the total area of the garden. b) The garden is \(15\,\text{m}\) wide. Find its length.

Hints

- Use the known area and percent to find the whole garden area. - For a rectangle, how are area, length, and width related?

Solution

1. The flower bed is \(14\%\) of the garden, so the garden’s area is \(12.6\,\text{m}^2 \div 0.14 = 90\,\text{m}^2\). 2. For a rectangle, length equals area divided by width: \(90\,\text{m}^2 \div 15\,\text{m} = 6\,\text{m}\).

Answer

a) \(90\,\text{m}^2\) b) \(6\,\text{m}\)
5114176
A rain barrel is \(35\%\) full. After \(130\,\text{L}\) of rainwater is added, it is \(60\%\) full. a) What is the barrel’s total capacity? b) How much more water is needed to fill the barrel completely?

Hints

- Find what percent of the capacity the added \(130\,\text{L}\) represents. - Use that part to find the whole capacity. - Then find the percent still missing from a full barrel.

Solution

1. The added water changed the level by \(60\% - 35\% = 25\%\) of the barrel’s capacity. 2. Since \(25\%\) is \(130\,\text{L}\), the full capacity is \(130\,\text{L} \div 0.25 = 520\,\text{L}\). 3. The barrel is missing \(100\% - 60\% = 40\%\) of its capacity. 4. The missing volume is \(520\,\text{L} \times 0.40 = 208\,\text{L}\).

Answer

a) \(520\,\text{L}\) b) \(208\,\text{L}\)
5114516
A class was surveyed about favorite sports. Of the students, \(25\%\) chose soccer, \(40\%\) chose swimming, and the rest chose track and field. What fraction of the class chose track and field? Write the fraction in simplest form.

Hints

- What percent do all responses total? - What percent remains after subtracting the other two sports? - Write the remaining percent as a fraction, then simplify.

Solution

1. Add the percents for soccer and swimming: \(25\% + 40\% = 65\%\). 2. Subtract from \(100\%\) to find the percent who chose track and field: \(100\% - 65\% = 35\%\). 3. Write \(35\%\) as a fraction: \(35\% = \frac{35}{100}\). 4. Simplify by dividing the numerator and denominator by \(5\): \(\frac{35}{100} = \frac{7}{20}\).

Answer

\(\frac{7}{20}\)
5114576
The same portion can be written in different forms: A: \(\frac{7}{20}\) B: \(34\%\) C: \(0.36\) D: \(\frac{18}{50}\) Write each value as a percent. Then identify the two expressions that represent the same portion.

Hints

- First write every value as a percent. - For each fraction, try to make the denominator \(100\). - Which two percent values are equal?

Solution

1. For A, \(\frac{7}{20} = \frac{35}{100} = 35\%\). 2. Value B is already written as \(34\%\). 3. For C, \(0.36 = 36\%\). 4. For D, \(\frac{18}{50} = \frac{36}{100} = 36\%\). 5. Values C and D are equal because both represent \(36\%\).

Answer

A: \(35\%\); B: \(34\%\); C: \(36\%\); D: \(36\%\). C and D represent the same portion.
5114606
Find the missing value \(x\) so that the sum equals \(1\), or \(100\%\). Write your answer as a fraction in simplest form, a decimal, and a percent. \(\frac{1}{5} + 0.35 + 15\% + x = 1\)

Hints

- Write all the portions in the same form before adding. - How much is missing from \(100\%\)? - Once you have the decimal, how can you write it as a fraction and a percent?

Solution

1. Write the given values as decimals: \(\frac{1}{5} = 0.2\), \(0.35 = 0.35\), and \(15\% = 0.15\). 2. Add the known values: \(0.2 + 0.35 + 0.15 = 0.7\). 3. Subtract from \(1\): \(x = 1 - 0.7 = 0.3\). 4. Convert \(0.3\) to the other forms: \(0.3 = \frac{3}{10} = 30\%\).

Answer

Fraction: \(\frac{3}{10}\); decimal: \(0.3\); percent: \(30\%\)
5114626
A fraction can be written as a whole-number percent only when \(100\) times its numerator is divisible by its denominator. Use this rule to explain why \(\frac{5}{14}\) cannot be written as a whole-number percent.

Hints

- What does it mean for one number to be divisible by another? - Divide \(500\) by \(14\) and check whether there is a remainder.

Solution

1. Multiply the numerator by \(100\): \(5 \times 100 = 500\). 2. Check whether \(500\) is divisible by the denominator, \(14\). 3. Divide: \(500 \div 14 = 35\) remainder \(10\), or \(35.714\ldots\). 4. Because the division has a remainder, \(\frac{5}{14}\) cannot be written as a whole-number percent.

Answer

\(\frac{5}{14}\) cannot be written as a whole-number percent because \(500\) is not divisible by \(14\): \(500 \div 14 = 35\) remainder \(10\).
5114666
A soil sample contains these main materials: - Sand: \(\frac{3}{8}\) - Clay: \(0.45\) - The rest is humus. Find the percent of the sample that is humus. Is the humus portion greater than \(\frac{1}{10}\) of the sample? Justify your answer.

Hints

- What percent do all the materials total? - Convert \(\frac{3}{8}\) to a decimal or percent. - What percent is one tenth? - First find the total percent represented by sand and clay.

Solution

1. Convert the sand portion: \(\frac{3}{8} = 0.375 = 37.5\%\). 2. Convert the clay portion: \(0.45 = 45\%\). 3. Add the known portions: \(37.5\% + 45\% = 82.5\%\). 4. Subtract from the whole: \(100\% - 82.5\% = 17.5\%\). 5. Since \(\frac{1}{10} = 10\%\) and \(17.5\% > 10\%\), the humus portion is greater than \(\frac{1}{10}\).

Answer

The humus portion is \(17.5\%\). Yes, it is greater than \(\frac{1}{10}\), which is \(10\%\).
5114696
Complete the table. Write each fraction in simplest form. <table> <tr> <th>Fraction</th> <th>Decimal</th> <th>Percent</th> </tr> <tr> <td>\(\frac{4}{25}\)</td> <td>?</td> <td>?</td> </tr> <tr> <td>?</td> <td>\(0.08\)</td> <td>?</td> </tr> <tr> <td>\(\frac{13}{20}\)</td> <td>?</td> <td>?</td> </tr> <tr> <td>?</td> <td>?</td> <td>\(120\%\)</td> </tr> </table>

Hints

- A denominator of \(100\) is useful when converting between fractions and percents. - How are hundredths related to two decimal places?

Solution

1. Row 1: \(\frac{4}{25} = \frac{16}{100}\), so the decimal is \(0.16\) and the percent is \(16\%\). 2. Row 2: \(0.08 = 8\%\). As a fraction, \(0.08 = \frac{8}{100} = \frac{2}{25}\). 3. Row 3: \(\frac{13}{20} = \frac{65}{100}\), so the decimal is \(0.65\) and the percent is \(65\%\). 4. Row 4: \(120\% = 1.20 = 1.2\). As a fraction, \(120\% = \frac{120}{100} = \frac{6}{5}\).

Answer

Row 1: \(0.16\); \(16\%\) Row 2: \(\frac{2}{25}\); \(8\%\) Row 3: \(0.65\); \(65\%\) Row 4: \(\frac{6}{5}\); \(1.2\)
5114726
A survey records how residents of a town travel to work. The portions are written in different forms: - Bicycle: \(0.28\) - Walking: \(\frac{7}{25}\) - Bus: \(\frac{9}{40}\) - Car: \(\frac{105}{500}\) a) Write all four portions as percents. b) Add the four percents. What percent is missing from the whole, \(100\%\)?

Hints

- How do you write \(0.28\) directly as a percent? - Write all the portions in the same form before comparing or adding. - Add your results and compare the sum with \(100\%\).

Solution

1. Bicycle: \(0.28 = 28\%\). 2. Walking: \(\frac{7}{25} = \frac{28}{100} = 28\%\). 3. Bus: \(\frac{9}{40} = 0.225 = 22.5\%\). 4. Car: \(\frac{105}{500} = \frac{21}{100} = 21\%\). 5. Add the percents: \(28\% + 28\% + 22.5\% + 21\% = 99.5\%\). 6. Subtract from the whole: \(100\% - 99.5\% = 0.5\%\).

Answer

a) Bicycle: \(28\%\); walking: \(28\%\); bus: \(22.5\%\); car: \(21\%\) b) The total is \(99.5\%\), so \(0.5\%\) is missing.
5114866
Write each quantity as a decimal and as a percent. a) One-eighth of a whole b) Three-twentieths c) Seven out of ten d) Twice \(1.5\%\) e) One-fourth of \(10\%\)

Hints

- Percent means “per hundred.” - Convert a fraction to a decimal by dividing the numerator by the denominator. - For phrases such as “seven out of ten,” first write a fraction.

Solution

1. For part a), \(\frac{1}{8} = 0.125 = 12.5\%\). 2. For part b), \(\frac{3}{20} = 0.15 = 15\%\). 3. For part c), \(\frac{7}{10} = 0.7 = 70\%\). 4. For part d), \(2 \times 1.5\% = 3\% = 0.03\). 5. For part e), \(\frac{1}{4} \times 10\% = 2.5\% = 0.025\).

Answer

a) \(0.125\) and \(12.5\%\) b) \(0.15\) and \(15\%\) c) \(0.7\) and \(70\%\) d) \(0.03\) and \(3\%\) e) \(0.025\) and \(2.5\%\)
5115286
A school library has \(45\) mystery books for young readers. These books make up \(15\%\) of its young-reader collection. First find the total number of books in the collection. Then find the number of fantasy books if they make up \(20\%\) of the collection.

Hints

- Find the total collection before finding the fantasy category. - Use the known part and percent to find \(100\%\). - Then find \(20\%\) of the total.

Solution

1. Since \(45\) is \(15\%\) of the collection, the total is \(45 \div 0.15 = 300\) books. 2. Fantasy books make up \(20\%\) of \(300\): \(300 \times 0.20 = 60\).

Answer

There are \(300\) books in the collection and \(60\) fantasy books.
5115406
The part is \(24\). Find the whole, \(G\), for each percent, and order the wholes from least to greatest. a) \(50\%\) b) \(20\%\) c) \(3\%\)

Hints

- Find each whole separately. - Consider how the whole changes when the same part represents a smaller percent.

Solution

1. Divide \(24\) by each percent written as a decimal. 2. a) \(24 \div 0.50 = 48\) 3. b) \(24 \div 0.20 = 120\) 4. c) \(24 \div 0.03 = 800\) 5. Therefore, \(48 < 120 < 800\).

Answer

a) \(G = 48\) b) \(G = 120\) c) \(G = 800\) Order: \(48 < 120 < 800\)
5115416
Find \(x\) in each statement. a) \(15\%\) of \(x\) is \(\$45\). b) \(75\%\) of \(x\) is \(90\,\text{kg}\). c) \(12.5\%\) of \(x\) is \(10\). d) \(40\%\) of \(x\) is \(14\,\text{m}\).

Hints

- Keep each unit in the answer. - It may help to write \(75\%\) as \(\frac{3}{4}\). - What simple fraction is equivalent to \(12.5\%\)?

Solution

1. Divide each part by the percent written as a decimal. 2. a) \(x = \$45 \div 0.15 = \$300\) 3. b) \(x = 90\,\text{kg} \div 0.75 = 120\,\text{kg}\) 4. c) \(x = 10 \div 0.125 = 80\) 5. d) \(x = 14\,\text{m} \div 0.40 = 35\,\text{m}\)

Answer

a) \(x = \$300\) b) \(x = 120\,\text{kg}\) c) \(x = 80\) d) \(x = 35\,\text{m}\)
5115536
Consider this statement about reading habits: “Ten years ago, one out of every ten children read a book every day. Today the situation has improved because only one out of every eight children reads a book every day. Our goal is for \(5\%\) of children to read a book every day again soon.” Explain why the statement is illogical. Then revise it so that it describes a real improvement and a reasonable goal.

Hints

- Find the percents for one out of every ten and one out of every eight. - Does a larger portion represent an improvement in this situation? - Is a goal of \(5\%\) higher or lower than the current value?

Solution

1. One out of every ten is \(\frac{1}{10} = 10\%\). One out of every eight is \(\frac{1}{8} = 12.5\%\). 2. An increase from \(10\%\) to \(12.5\%\) is an improvement, but the word “only” suggests a decrease. 3. A goal of \(5\%\) is lower than both \(10\%\) and \(12.5\%\), so it would not represent improvement. The word “again” also conflicts with the earlier value of \(10\%\). 4. One possible revision is: “Ten years ago, one out of every ten children, or \(10\%\), read a book every day. Today the situation has improved because one out of every eight children, or \(12.5\%\), reads a book every day. Our goal is for one out of every five children, or \(20\%\), to read a book every day.”

Answer

The statement is illogical because one out of every eight, or \(12.5\%\), is greater than one out of every ten, or \(10\%\), so “only” does not fit. Also, a goal of \(5\%\) would be lower than both earlier values. Revised statement: “Ten years ago, one out of every ten children, or \(10\%\), read a book every day. Today the situation has improved because one out of every eight children, or \(12.5\%\), reads a book every day. Our goal is for one out of every five children, or \(20\%\), to read a book every day.”
5115646
Noah and Ava are each saving for a mountain bike. Noah has saved \(\$108\), which is \(45\%\) of his goal. Ava has saved \(\$140\), which is \(70\%\) of her goal. Who plans to buy the more expensive bike? Find both prices and their difference.

Hints

- Find \(100\%\) of each person’s savings goal separately. - Compare the two prices, then subtract to find the difference.

Solution

1. Noah’s goal is \(\$108 \div 0.45 = \$240\). 2. Ava’s goal is \(\$140 \div 0.70 = \$200\). 3. Since \(\$240 > \$200\), Noah plans to buy the more expensive bike. 4. The price difference is \(\$240 - \$200 = \$40\).

Answer

Noah’s bike costs \(\$240\), Ava’s costs \(\$200\), and the difference is \(\$40\). Noah plans to buy the more expensive bike.
5116066
A fraction has the form \(\frac{x}{40}\), where \(x\) is a positive whole number. a) Explain mathematically why \(\frac{x}{40}\) is a whole-number percent only when \(x\) is even. b) Give two values of \(x\) that produce whole-number percents and two values that do not. Find each percent.

Hints

- Simplify \(\frac{100}{40}\) first. - When is \(2.5x\) a whole number? - Test several small values of \(x\) and look for a pattern.

Solution

1. Convert the fraction to a percent: \(\frac{x}{40} \times 100 = \frac{100x}{40}\). 2. Simplify: \(\frac{100x}{40} = \frac{5x}{2} = 2.5x\). 3. For \(\frac{5x}{2}\) to be a whole number, \(x\) must be divisible by \(2\), so \(x\) must be even. 4. For example, if \(x = 2\), then \(\frac{2}{40} = 5\%\). If \(x = 4\), then \(\frac{4}{40} = 10\%\). 5. If \(x = 1\), then \(\frac{1}{40} = 2.5\%\). If \(x = 3\), then \(\frac{3}{40} = 7.5\%\).

Answer

a) \(\frac{x}{40} \times 100 = \frac{5x}{2}\). This is a whole number only when \(x\) is even. b) Examples that give whole-number percents: \(x = 2\), which gives \(5\%\), and \(x = 4\), which gives \(10\%\). Examples that do not: \(x = 1\), which gives \(2.5\%\), and \(x = 3\), which gives \(7.5\%\).
5117456
In a sports club, \(45\%\) of the members play soccer. That group has \(54\) members. How many club members participate in other sports?

Hints

- First find the total number of club members. - Then subtract the soccer group, or find the remaining percent.

Solution

1. Find the total membership: \(54 \div 0.45 = 120\). 2. Subtract the soccer members: \(120 - 54 = 66\). 3. Equivalently, the other sports represent \(100\% - 45\% = 55\%\), and \(120 \times 0.55 = 66\).

Answer

\(66\) members participate in other sports.
5117496
In a class election, Jordan received \(9\) votes, which was \(30\%\) of all votes cast. Casey received \(6\) votes, and the remaining votes went to Riley. a) How many students voted? b) What percent of the votes did Casey receive? c) How many votes did Riley receive, and what percent was that?

Hints

- Use the known \(30\%\) share to find all votes. - The vote counts must total the number found in part a). - The percentages must total \(100\%\).

Solution

1. Since \(9\) votes is \(30\%\) of the total, the total number of votes is \(9 \div 0.30 = 30\). 2. Casey’s share is \(\frac{6}{30} \times 100\% = 20\%\). 3. Riley received \(30 - 9 - 6 = 15\) votes. 4. Riley’s share is \(\frac{15}{30} \times 100\% = 50\%\).

Answer

a) \(30\) students b) \(20\%\) c) \(15\) votes, or \(50\%\)
5117536
Students in a class identified their favorite free-time activities: - \(\frac{1}{5}\) of the class plays an instrument. - \(0.32\) of the class plays on a sports team. - \(\frac{6}{25}\) of the class enjoys reading. - The rest chose “Other.” Find the percent of the class in each group.

Hints

- What percent do all four groups total? - How can you write a decimal directly as hundredths? - Write all the given portions with denominator \(100\).

Solution

1. Convert the given portions: instrument, \(\frac{1}{5} = \frac{20}{100} = 20\%\); sports team, \(0.32 = 32\%\); reading, \(\frac{6}{25} = \frac{24}{100} = 24\%\). 2. Add the known percents: \(20\% + 32\% + 24\% = 76\%\). 3. Subtract from the whole: \(100\% - 76\% = 24\%\).

Answer

Instrument: \(20\%\) Sports team: \(32\%\) Reading: \(24\%\) Other: \(24\%\)
5117546
Determine whether each statement is true or false. Convert the fractions to percents and show your reasoning. a) \(\frac{1}{3}\) is greater than \(33\%\). b) \(\frac{5}{8}\) is exactly \(62.5\%\). c) If \(\frac{1}{12}\) of a pizza is eaten, less than \(90\%\) of the pizza remains.

Hints

- Divide the numerator by the denominator when the fraction cannot easily be written with denominator \(100\). - What happens when you divide \(1\) by \(3\)? - Subtract the percent eaten from \(100\%\) to find the percent remaining.

Solution

1. For a), \(\frac{1}{3} = 0.333\ldots = 33.333\ldots\%\). Since \(33.333\ldots\% > 33\%\), the statement is true. 2. For b), \(\frac{5}{8} = 0.625 = 62.5\%\). The statement is true. 3. For c), \(\frac{1}{12} = 0.08333\ldots = 8.333\ldots\%\). The remaining portion is \(100\% - 8.333\ldots\% = 91.666\ldots\%\). Since this is greater than \(90\%\), the statement is false.

Answer

a) True, because \(\frac{1}{3} = 33.333\ldots\% > 33\%\). b) True, because \(\frac{5}{8} = 0.625 = 62.5\%\). c) False. \(91.666\ldots\%\) remains, which is greater than \(90\%\).
5117776
Write each fraction as a percent. Round to the nearest tenth of a percent. 1. \(\frac{5}{12}\) 2. \(\frac{4}{7}\) 3. \(\frac{11}{15}\)

Hints

- Divide the numerator by the denominator when the fraction cannot easily be written with denominator \(100\). - Use the usual rounding rule for the hundredths digit of the percent. - Calculate enough decimal places to round to the nearest tenth of a percent.

Solution

1. \(5 \div 12 = 0.41666\ldots\), so \(\frac{5}{12} = 41.666\ldots\% \approx 41.7\%\). 2. \(4 \div 7 = 0.571428\ldots\), so \(\frac{4}{7} = 57.1428\ldots\% \approx 57.1\%\). 3. \(11 \div 15 = 0.73333\ldots\), so \(\frac{11}{15} = 73.333\ldots\% \approx 73.3\%\).

Answer

1. \(\approx 41.7\%\) 2. \(\approx 57.1\%\) 3. \(\approx 73.3\%\)
5118466
Find each portion as a decimal and as a percent. a) In a bag of gummy bears, \(12\) out of \(40\) are red. b) In a survey, one out of every eight people answered “Yes.” c) A town has \(2000\) residents, and \(15\) serve on the town council. d) A computer drive has \(\frac{3}{8}\) of its storage space filled.

Hints

- Write each portion as a fraction first. - Divide the numerator by the denominator to find the decimal. - Multiply the decimal by \(100\) to find the percent.

Solution

1. For part a, \(\frac{12}{40} = \frac{3}{10} = 0.3 = 30\%\). 2. For part b, \(\frac{1}{8} = 0.125 = 12.5\%\). 3. For part c, \(\frac{15}{2000} = 0.0075 = 0.75\%\). 4. For part d, \(\frac{3}{8} = 0.375 = 37.5\%\).

Answer

a) \(0.3\), \(30\%\) b) \(0.125\), \(12.5\%\) c) \(0.0075\), \(0.75\%\) d) \(0.375\), \(37.5\%\)
5118476
Write each portion as a decimal and as a percent. a) A metal mixture contains \(2\,\text{g}\) of gold and \(498\,\text{g}\) of copper. What portion of the total mass is gold? b) A model car is built at a scale of \(1 : 200\). What portion of the corresponding full-size length is a length on the model? c) A drink contains \(5\,\text{mL}\) of syrup in a total volume of \(1\,\text{L}\).

Hints

- For part a, find the total mass first. - For part c, convert the measurements to the same unit. - A scale of \(1 : 200\) means a model length is \(\frac{1}{200}\) of the corresponding full-size length.

Solution

1. For part a, the total mass is \(2\,\text{g} + 498\,\text{g} = 500\,\text{g}\). The gold portion is \(\frac{2}{500} = 0.004 = 0.4\%\). 2. For part b, the scale portion is \(\frac{1}{200} = 0.005 = 0.5\%\). 3. For part c, \(1\,\text{L} = 1000\,\text{mL}\). The syrup portion is \(\frac{5}{1000} = 0.005 = 0.5\%\).

Answer

a) \(0.004\), \(0.4\%\) b) \(0.005\), \(0.5\%\) c) \(0.005\), \(0.5\%\)
5118786
A number is unknown, but \(20\%\) of the number is \(48\). a) Find the whole number. b) Find \(75\%\) of that number. c) A student says, “Because \(75\%\) is \(3.75\) times \(20\%\), I can multiply \(48\) by \(3.75\) to answer part b).” Check the student's claim with a calculation.

Hints

- If \(20\%\) is \(48\), how can you use that information to find \(100\%\)? - Can you find the answer to part b) without first finding the whole? - Think about how the part changes when the percent changes but the whole stays the same.

Solution

1. The whole number is \(48 \div 0.20 = 240\). 2. Then \(75\%\) of the whole is \(240 \times 0.75 = 180\). 3. To check the claim, compute \(48 \times 3.75 = 180\). This matches the result from part b), so the claim is correct.

Answer

a) \(240\) b) \(180\) c) The claim is correct because \(48 \times 3.75 = 180\).
5118976
A smartphone battery has a total capacity of \(4500\,\text{mAh}\) (milliamp-hours). a) The battery currently stores \(1125\,\text{mAh}\). What percent of its full capacity is this? b) The phone automatically enters low-power mode when the charge reaches \(20\%\). How much charge remains at that point? c) Without being charged, the battery level drops from \(20\%\) to \(5\%\). How much charge, in \(\text{mAh}\), was used during that drop?

Hints

- Identify the full capacity and the amount of charge in each part. - How do you find a percent when the part and the whole are known? - For c), first find the change in the battery percentage. - Include the correct unit in each charge amount.

Solution

1. The current percent is \(\frac{1125}{4500} = 0.25 = 25\%\). 2. At \(20\%\), the remaining charge is \(4500\,\text{mAh} \times 0.20 = 900\,\text{mAh}\). 3. The battery level drops by \(20 - 5 = 15\) percentage points. This amount is \(15\%\) of the full capacity, so the charge used is \(4500\,\text{mAh} \times 0.15 = 675\,\text{mAh}\).

Answer

a) \(25\%\) b) \(900\,\text{mAh}\) c) \(675\,\text{mAh}\)
5118986
As part of a reforestation project, \(420\) young oak trees were planted. The oaks make up exactly \(35\%\) of all the trees planted in that area this year. a) How many trees were planted in all? b) All the other new trees are beech trees. What percent of the trees are beeches? c) How many beech trees were planted?

Hints

- When a part and its percent are known, what calculation finds the whole? - The percentages for all tree types must add to \(100\%\). - After finding the total, can you subtract the number of oaks to find the number of beeches?

Solution

1. The total number of trees is \(420 \div 0.35 = 1200\). 2. The percent that are beeches is \(100\% - 35\% = 65\%\). 3. The number of beeches is \(1200 - 420 = 780\). Equivalently, \(1200 \times 0.65 = 780\).

Answer

a) \(1200\) trees b) \(65\%\) c) \(780\) beech trees
5142596
In a school survey, \(162\) students said they regularly play a musical instrument. This is \(27\%\) of all the students surveyed. a) How many students were surveyed in all? b) Of the students surveyed, \(45\%\) said they play on a sports team. How many students is that? c) Next year, \(18\) additional students begin playing an instrument, while the total number surveyed stays the same. What percent of the students will then play an instrument?

Hints

- Use the number of instrument players and its percent to find the total number surveyed. - After finding the total, multiply it by the percent who play on a sports team. - For c), update the number of instrument players but keep the same total.

Solution

1. The total number surveyed is \(162 \div 0.27 = 600\). 2. The number who play on a sports team is \(600 \times 0.45 = 270\). 3. The new number who play an instrument is \(162 + 18 = 180\). 4. The new percent is \(\frac{180}{600} = 0.30 = 30\%\).

Answer

a) \(600\) students b) \(270\) students c) \(30\%\)
5142736
Two percent situations are given. Find the whole in each case, and determine which whole is greater. Case 1: part \(= 35\); percent \(= 14\%\) Case 2: part \(= 60\); percent \(= 25\%\)

Hints

- When the part and percent are known, divide the part by the percent written as a decimal. - Find the two wholes separately before comparing them.

Solution

1. For Case 1, the whole is \(35 \div 0.14 = 250\). 2. For Case 2, the whole is \(60 \div 0.25 = 240\). 3. Since \(250 > 240\), the whole in Case 1 is greater.

Answer

Case 1: \(250\) Case 2: \(240\) The whole in Case 1 is greater.
5318856
The circle graph shows the categories in a school library. The library has exactly \(90\) graphic novels. a) How many books are in the library altogether? b) How many nonfiction books are in the library?
Figure for problem 531885

Hints

- Read the graphic-novel percent from the graph. - Use the known \(15\%\) part to find \(100\%\). - Then find \(45\%\) of the total.

Solution

1. Graphic novels represent \(15\%\) of the collection. 2. Since \(90\) is \(15\%\), the total number of books is \(90 \div 0.15 = 600\). 3. Nonfiction books represent \(45\%\) of the collection: \(600 \times 0.45 = 270\).

Answer

a) \(600\) books b) \(270\) nonfiction books
5318996
A family tracks its monthly spending. The circle graph shows the percent used for each category. The family spends \(\$450\) on groceries, which is \(30\%\) of its monthly budget. a) Find the total monthly budget. b) How much does the family spend on rent, entertainment, and other expenses?
Figure for problem 531899

Hints

- Use the grocery amount and its percent to find the whole budget. - Once you know the total, multiply it by each remaining percent.

Solution

1. Since \(\$450\) is \(30\%\) of the budget, the total is \(\$450 \div 0.30 = \$1500\). 2. Rent: \(\$1500 \times 0.40 = \$600\). 3. Entertainment: \(\$1500 \times 0.15 = \$225\). 4. Other expenses: \(\$1500 \times 0.15 = \$225\).

Answer

a) \(\$1500\) b) Rent: \(\$600\); entertainment: \(\$225\); other expenses: \(\$225\)
5319066
A survey asked students about their favorite free-time activity. The circle graph shows the results. Exactly \(120\) students chose sports, which represents \(30\%\) of those surveyed. a) How many students were surveyed? b) How many students chose gaming, music, and reading, respectively?
Figure for problem 531906

Hints

- Match the \(120\) students with the sports percent. - Use that part to find the whole survey group. - Then multiply the total by each other percent.

Solution

1. Since \(120\) is \(30\%\) of the group, the total is \(120 \div 0.30 = 400\) students. 2. Gaming: \(400 \times 0.40 = 160\). 3. Music: \(400 \times 0.20 = 80\). 4. Reading: \(400 \times 0.10 = 40\).

Answer

a) \(400\) students b) Gaming: \(160\); music: \(80\); reading: \(40\)
5319106
The circle graph shows how students travel to school. A survey found that \(120\) students ride a bicycle. a) How many students attend the school? b) How many students travel by bus, how many walk, and how many travel by car?
Figure for problem 531910

Hints

- Read the bicycle percent from the graph. - Use the \(120\) bicycle riders to find the total number of students. - Check that all four travel groups add to the total.

Solution

1. Bicycle riders represent \(25\%\) of the students, so the total enrollment is \(120 \div 0.25 = 480\). 2. Bus: \(480 \times 0.40 = 192\). 3. Walking: \(480 \times 0.20 = 96\). 4. Car: \(480 \times 0.15 = 72\).

Answer

a) \(480\) students b) Bus: \(192\); walking: \(96\); car: \(72\)
5355066
A \(5 \times 5\) grid shows the planned floor of a small patio. The shaded border tiles are already installed and cover \(4.48\,\text{m}^2\). What will the area of the entire patio be?
Figure for problem 535506

Hints

- Count the total tiles and the shaded border tiles. - Express the shaded portion as a fraction or percent of the grid. - Use the shaded area to find the whole area.

Solution

1. The grid has \(5 \times 5 = 25\) equal tiles, and \(16\) border tiles are shaded. 2. The installed border is \(\frac{16}{25} = 0.64 = 64\%\) of the patio. 3. Since \(4.48\,\text{m}^2\) is \(64\%\) of the total, the patio area is \(4.48\,\text{m}^2 \div 0.64 = 7\,\text{m}^2\).

Answer

The entire patio has an area of \(7\,\text{m}^2\).
5356226
A local radio station plays several music genres throughout the day. The pie chart shows the percent of songs in each genre. On one day, the station played exactly \(12\) jazz songs. a) How many songs did the station play in all that day? b) How many of the songs were pop songs?
Figure for problem 535622

Hints

- You know the number represented by \(15\%\). Use it to find the whole, or \(100\%\). - After finding the total number of songs, multiply it by the pop percentage. - A percent table can help: if \(15\%\) corresponds to \(12\), what corresponds to \(1\%\)?

Solution

1. Jazz songs make up \(15\%\) of the total. Therefore, the total number of songs is \(12 \div 0.15 = 80\). 2. Pop songs make up \(40\%\) of the total, so the number of pop songs is \(80 \times 0.40 = 32\).

Answer

a) \(80\) songs b) \(32\) pop songs
5357676
Look at the three figures. For each figure, find the shaded portion of the whole. Write each result as a fraction in simplest form, a decimal, and a percent.
Figure for problem 535767

Hints

- Count the equal parts in each whole to find the denominator. - Count the shaded parts to find the numerator. - Write each fraction with denominator \(10\), \(100\), or \(1000\) when possible. - Percent means “per hundred.”

Solution

1. Count the shaded parts and total parts: a) \(\frac{11}{20}\) b) \(\frac{7}{10}\) c) \(\frac{8}{25}\) 2. Convert to decimals: a) \(\frac{11}{20} = \frac{55}{100} = 0.55\) b) \(\frac{7}{10} = 0.7\) c) \(\frac{8}{25} = \frac{32}{100} = 0.32\) 3. Convert to percents: a) \(0.55 = 55\%\) b) \(0.7 = 70\%\) c) \(0.32 = 32\%\)

Answer

a) \(\frac{11}{20} = 0.55 = 55\%\) b) \(\frac{7}{10} = 0.7 = 70\%\) c) \(\frac{8}{25} = 0.32 = 32\%\)
5109656
A community center divides its renovation budget among three categories. Paint and wall coverings use \(37.5\%\) of the budget, and new furniture uses one third. The remaining \(\$1050\) is used for sports equipment. What was the total renovation budget?

Hints

- Write the percent and the fraction with compatible forms. - Find the fraction of the budget left for sports equipment. - Use the value of that fraction to find the whole budget.

Solution

1. Write \(37.5\%\) as a fraction: \(37.5\% = \frac{3}{8}\). 2. Paint, wall coverings, and furniture use \(\frac{3}{8} + \frac{1}{3} = \frac{9}{24} + \frac{8}{24} = \frac{17}{24}\) of the budget. 3. Sports equipment uses \(1 - \frac{17}{24} = \frac{7}{24}\) of the budget. 4. Since \(\frac{7}{24}\) equals \(\$1050\), the whole budget is \(\$1050 \times \frac{24}{7} = \$3600\).

Answer

The total renovation budget was \(\$3600\).
5114636
Consider fractions with denominator \(16\) in the form \(\frac{k}{16}\). Find all whole-number values of \(k\) from \(1\) through \(10\) for which the fraction is equal to a whole-number percent. Explain your reasoning.

Hints

- Multiply the numerator by \(100\) and check whether the result is divisible by \(16\). - Can you simplify \(\frac{100}{16}\) first? - Look for a pattern in the values of \(k\) that work.

Solution

1. For the percent to be a whole number, \(\frac{100k}{16}\) must be a whole number. 2. Simplify the expression: \(\frac{100k}{16} = \frac{25k}{4}\). 3. Since \(25\) is not divisible by \(4\), \(k\) must be a multiple of \(4\). 4. The multiples of \(4\) from \(1\) through \(10\) are \(4\) and \(8\). 5. Check: \(\frac{4}{16} = 25\%\) and \(\frac{8}{16} = 50\%\).

Answer

The values are \(k = 4\) and \(k = 8\). For these values, \(100k\) is divisible by \(16\): \(400 \div 16 = 25\) and \(800 \div 16 = 50\).
5115296
Alex spent \(\$18\) on a video game and says, “That was exactly \(60\%\) of my savings. Had I saved \(\$10\) more, the game would have cost only \(45\%\) of my savings.” Determine Alex’s actual savings and verify whether the statement is correct.

Hints

- First use \(\$18\) and \(60\%\) to find the original savings. - Add \(\$10\), then find what percent \(\$18\) is of the new amount. - Compare that percent with \(45\%\).

Solution

1. Since \(\$18\) is \(60\%\) of the savings, the actual savings were \(\$18 \div 0.60 = \$30\). 2. With \(\$10\) more, the savings would have been \(\$30 + \$10 = \$40\). 3. The game would then represent \(\frac{18}{40} \times 100\% = 45\%\). 4. This matches the claim, so the statement is correct.

Answer

Alex had saved \(\$30\). The statement is correct because \(\$18\) is \(45\%\) of \(\$40\).
5115526
A radio station reports on a recycling survey: “In our city, one out of every eight households does not sort its recycling correctly. That is nearly half of all households, exactly \(25\%\). We need to reach our goal of \(10\%\), or one out of every twenty households.” Find the three mathematical errors. Then write a corrected version of the report.

Hints

- Write “one out of every eight,” “half,” and “one out of every twenty” as percents. - Compare those values with the percents stated in the report. - Check whether the phrase “nearly half” matches the actual value.

Solution

1. “One out of every eight” means \(\frac{1}{8} = 12.5\%\), not \(25\%\). 2. Half is \(50\%\). A value of \(12.5\%\) is not nearly half. 3. A goal of \(10\%\) means \(\frac{10}{100} = \frac{1}{10}\), or one out of every ten households. One out of every twenty is \(\frac{1}{20} = 5\%\). 4. A corrected report is: “In our city, one out of every eight households, or \(12.5\%\), does not sort its recycling correctly. We need to reach our goal of \(10\%\), or one out of every ten households.”

Answer

The errors are: 1. One out of every eight is \(12.5\%\), not \(25\%\). 2. \(12.5\%\) is not nearly half, which is \(50\%\). 3. \(10\%\) means one out of every ten, not one out of every twenty, which is \(5\%\). Corrected report: “In our city, one out of every eight households, or \(12.5\%\), does not sort its recycling correctly. We need to reach our goal of \(10\%\), or one out of every ten households.”
5116076
One way to convert a fraction to a percent is to simplify or scale it until the denominator is \(100\). Compare \(\frac{6}{15}\) and \(\frac{6}{14}\). One can be written as a whole-number percent, but the other cannot. Simplify both fractions completely, then use their denominators to explain the difference.

Hints

- Simplify both fractions completely first. - What are the prime factors of \(100\)? - Can a fraction with denominator \(7\) be scaled to denominator \(100\) using whole numbers?

Solution

1. Simplify \(\frac{6}{15}\) by dividing by \(3\): \(\frac{6}{15} = \frac{2}{5}\). Since \(5\) is a factor of \(100\), multiply by \(\frac{20}{20}\): \(\frac{2}{5} = \frac{40}{100} = 40\%\). 2. Simplify \(\frac{6}{14}\) by dividing by \(2\): \(\frac{6}{14} = \frac{3}{7}\). Since \(7\) is not a factor of \(100\), the fraction cannot be scaled to a fraction with denominator \(100\) using whole numbers. Its percent is \(42.857\ldots\%\), not a whole number. 3. The difference is whether the denominator of the fraction in simplest form is a factor of \(100\).

Answer

\(\frac{6}{15} = \frac{2}{5} = 40\%\) because \(5\) is a factor of \(100\). \(\frac{6}{14} = \frac{3}{7} = 42.857\ldots\%\), which is not a whole-number percent because \(7\) is not a factor of \(100\). The denominator of the fraction in simplest form determines whether it can be written as an exact whole-number percent.
5117516
A school library has \(108\) nonfiction books, which is \(12\%\) of its collection. Novels make up \(35\%\) of the collection, and the remaining books are graphic novels. a) How many books are in the entire collection? b) How many novels are there? c) How many graphic novels are there, and what percent of the collection do they represent?

Hints

- Use the nonfiction category to find the entire collection. - Once you know the total, find \(35\%\) of it. - For the final category, find the percent left after the first two categories.

Solution

1. Since \(108\) is \(12\%\) of the collection, the total is \(108 \div 0.12 = 900\) books. 2. The number of novels is \(900 \times 0.35 = 315\). 3. Graphic novels represent \(100\% - 12\% - 35\% = 53\%\). 4. Their number is \(900 - 108 - 315 = 477\).

Answer

a) \(900\) books b) \(315\) novels c) \(477\) graphic novels, or \(53\%\) of the collection

All problems may be used, copied and printed free of charge for school and tutoring, including paid tutoring. Commercial adaptations as well as publication or redistribution on the internet are not permitted.