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Sample spaces for compound events

Learning goals

  • Lists or represents all outcomes in a sample space.
  • Uses tables, organized lists, or trees to avoid omissions and duplicates.
  • Defines events as subsets of the sample space.
  • Computes probabilities from the represented outcomes when appropriate.

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Sample spaces for compound events 1
A fair coin is flipped once and a spinner with \(3\) equal sections labeled \(1\), \(2\), and \(3\) is spun once. The table shows the sample space. <table> <tr> <th>Spinner result</th> <th>H</th> <th>T</th> </tr> <tr> <td>\(1\)</td> <td>\((1, H)\)</td> <td>\((1, T)\)</td> </tr> <tr> <td>\(2\)</td> <td>\((2, H)\)</td> <td>\((2, T)\)</td> </tr> <tr> <td>\(3\)</td> <td>\((3, H)\)</td> <td>\((3, T)\)</td> </tr> </table> a) How many equally likely outcomes are in the sample space? b) Which table entry represents spinning \(2\) and flipping tails?

Hints

- Each interior table cell represents one compound outcome. - For part b, locate the requested spinner row and coin column.

Solution

1. The table has \(3\) spinner rows and \(2\) coin columns, so it contains \(3\cdot2=6\) equally likely outcomes. 2. The row for \(2\) and the column for T intersect at \((2, T)\).

Answer

a) \(6\) b) \((2, T)\)
Sample spaces for compound events 2
Noor flips a coin twice and lists the possible results as H and T, where H means heads and T means tails. What information is missing from this list? Give two different possible results that the list treats as the same.

Hints

- How many flips happen in one trial? - Could the first and second flips give different results?

Solution

1. A complete result must state what happens on each of the two flips. 2. HT means heads then tails, while TH means tails then heads. 3. Noor's list does not distinguish those two results.

Answer

The list needs both flips in order. For example, HT and TH are different results.
Sample spaces for compound events 3
Which experiments have outcomes made from *two* chance actions? For each one, give an example of a complete result. a) Draw one colored card from a bag. b) Roll one number cube and flip a coin. c) Flip a coin twice. d) Spin one wheel once.

Hints

- A full outcome must tell everything that happened in the experiment. - Does each action happen once, or does another random action follow? - Check whether your example records every required result.

Solution

1. Part b has a roll and a flip, so a complete result could be rolling \(3\) and getting heads. 2. Part c has two flips, so a complete result could be heads followed by tails. 3. Parts a and d each use one chance action.

Answer

b) Roll a number cube and flip a coin: for example, roll \(3\) and get heads. c) Flip a coin twice: for example, heads then tails.
Sample spaces for compound events 4
A box has one red card and one blue card. A second box has a card marked X and a card marked Y. One card is picked from each box. List all possible color-letter results.

Hints

- Start with one card color and pair it with each letter. - Do the same for the other color.

Solution

1. With red, the possible pairs are red-X and red-Y. 2. With blue, they are blue-X and blue-Y. 3. These four pairs include every choice from the two boxes.

Answer

red-X, red-Y, blue-X, blue-Y.
Sample spaces for compound events 5
The garden club is choosing one flower (daisy, rose, or tulip) and one pot (clay or plastic). Every flower can go in either pot. Amara begins a list: daisy-clay, daisy-plastic, rose-clay, tulip-plastic Which choices are missing? How can you check that the completed list has every possible choice?

Hints

- Try organizing the choices by flower rather than by the order Amara wrote them. - How many pot choices should each flower have?

Solution

1. Organize the list by flower and check the two pots for each flower. 2. The rose-plastic and tulip-clay choices are missing. 3. Three flowers with two pot choices each give \(3\cdot2=6\) combinations, all of which appear after the missing two are added.

Answer

rose-plastic and tulip-clay. The complete list contains both pots for each of the three flowers, for \(6\) choices.
Sample spaces for compound events 6
Students choose one lunch (taco or pasta) and one drink (water, milk, or juice). Fill in the two missing entries in the table. <table> <tr><th></th><th>Water</th><th>Milk</th><th>Juice</th></tr> <tr><th>Taco</th><td>taco-water</td><td>?</td><td>taco-juice</td></tr> <tr><th>Pasta</th><td>?</td><td>pasta-milk</td><td>pasta-juice</td></tr> </table>

Hints

- Read the row label and column label for each question mark. - Each cell combines one lunch with one drink.

Solution

1. The missing cell in the Taco row and Milk column is taco-milk. 2. The missing cell in the Pasta row and Water column is pasta-water.

Answer

taco-milk; pasta-water.
Sample spaces for compound events 7
A game follows the paths in the tree. Some games end after one choice, while others have a second choice. How many different complete outcomes can the game have?
Figure for problem 559745

Hints

- A path counts only when it reaches its end. - Does every first branch split again?

Solution

1. The Stop path is one complete outcome. 2. The Play path splits into H and T, giving two more complete outcomes. 3. There are \(1+2=3\) complete outcomes.

Answer

\(3\) complete outcomes.
Sample spaces for compound events 8
The sample space \(S\) is the set of all possible outcomes of a random experiment. Write the sample space for each experiment: a) A fair spinner with four equal sections colored red (R), blue (B), yellow (Y), and green (G) is spun once. b) A coin with heads (H) and tails (T) is flipped twice. c) One number card is drawn from a bag containing cards labeled \(1\), \(3\), \(5\), and \(7\).

Hints

- Imagine performing each experiment. What could be recorded at the end? - For a multistep experiment, include every ordered combination of the stage outcomes. - Write sample spaces using braces and separate outcomes with commas.

Solution

1. a) One spin can result in any of the four colors, so \(S = \{\mathrm{R}, \mathrm{B}, \mathrm{Y}, \mathrm{G}\}\). 2. b) Each outcome records the first and second flips in order. Therefore, \(S = \{(\mathrm{H}, \mathrm{H}), (\mathrm{H}, \mathrm{T}), (\mathrm{T}, \mathrm{H}), (\mathrm{T}, \mathrm{T})\}\). 3. c) The possible outcomes are the labels on the cards, so \(S = \{1, 3, 5, 7\}\).

Answer

a) \(S = \{\mathrm{R}, \mathrm{B}, \mathrm{Y}, \mathrm{G}\}\) b) \(S = \{(\mathrm{H}, \mathrm{H}), (\mathrm{H}, \mathrm{T}), (\mathrm{T}, \mathrm{H}), (\mathrm{T}, \mathrm{T})\}\) c) \(S = \{1, 3, 5, 7\}\)
Sample spaces for compound events 9
A spinner has \(10\) equal sections labeled with the digits \(0\) through \(9\). It is spun twice. 1. Find the theoretical probability that the two results have a sum of exactly \(10\). 2. Find the probability that the product of the two results is odd. 3. In \(10{,}000\) computer-simulated trials, a sum of \(10\) occurred \(924\) times. Find the relative frequency and compare it with the theoretical probability.

Hints

- Use ordered pairs for the two spins. - A product is odd only when both factors are odd. - Relative frequency is successes divided by trials.

Solution

1. There are \(10\cdot10=100\) equally likely ordered pairs. The pairs with sum \(10\) are \((1, 9),(2, 8),(3, 7),(4, 6),(5, 5)\) and their reverses, for \(9\) outcomes. Thus, \(P=\frac{9}{100}=0.09\). 2. A product is odd only if both digits are odd. There are \(5\) odd digits, so \(P=\frac{5}{10}\cdot\frac{5}{10}=0.25\). 3. The relative frequency is \(\frac{924}{10000}=0.0924\), which is \(0.0024\) above the theoretical probability \(0.09\).

Answer

1. \(0.09\) 2. \(0.25\) 3. \(0.0924\), which is close to \(0.09\)
Sample spaces for compound events 10
Lara spins the \(8\)-section spinner shown twice. Find the probability that the spinner lands on red at least once. Give the answer as a simplified fraction and a percent.
Figure for problem 532095

Hints

- Count red sections from the spinner to find the one-spin red probability. - State the complement of “at least one red.” - Find the two-spin complement probability before subtracting from \(1\).

Solution

1. The spinner has \(2\) red sections out of \(8\), so \(P(\text{red})=\frac{1}{4}\) and \(P(\text{not red})=\frac{3}{4}\). 2. The probability of no red on either spin is \(\left(\frac{3}{4}\right)^2=\frac{9}{16}\). 3. Therefore, \(P(\text{at least one red})=1-\frac{9}{16}=\frac{7}{16}=43.75\%\).

Answer

\(\frac{7}{16}=43.75\%\)
Sample spaces for compound events 11
At a carnival booth, the \(10\)-section spinner shown is spun twice. a) Find the probability that both spins land on green. Give the answer as a percent. b) Find the probability that red occurs at least once.
Figure for problem 535985

Hints

- Count green and red sections from the spinner first. - Multiply the green probability for the two-spin event in part a. - For part b, use the complement of getting no red.

Solution

1. From the spinner, \(P(\text{green})=\frac{2}{10}=\frac{1}{5}\) and \(P(\text{red})=\frac{3}{10}\). 2. \(P(\text{green twice})=\frac{1}{5}\cdot\frac{1}{5}=\frac{1}{25}=4\%\). 3. The probability of not red on one spin is \(\frac{7}{10}\), so \(P(\text{at least one red})=1-\left(\frac{7}{10}\right)^2=\frac{51}{100}=51\%\).

Answer

a) \(4\%\) b) \(\frac{51}{100}=51\%\)
Sample spaces for compound events 12
The bag shown contains \(6\) lettered balls. One ball is drawn, replaced, and then a second ball is drawn. a) Find the probability of drawing the letter sequence “AN.” b) Find the probability of drawing “AA.”
Figure for problem 536148

Hints

- Read how many A and N balls are in the bag. - Replacement keeps the one-draw probabilities unchanged. - Multiply the probabilities in the requested order.

Solution

1. The bag shows \(3\) A balls, \(2\) N balls, and \(1\) B ball. Thus, \(P(A)=\frac{1}{2}\) and \(P(N)=\frac{1}{3}\). 2. Because the first ball is replaced, the probabilities stay the same on the second draw. 3. \(P(\text{AN})=\frac{1}{2}\cdot\frac{1}{3}=\frac{1}{6}\). 4. \(P(\text{AA})=\frac{1}{2}\cdot\frac{1}{2}=\frac{1}{4}\).

Answer

a) \(\frac{1}{6}\) b) \(\frac{1}{4}\)
Sample spaces for compound events 13
A bag contains five balls labeled \(1\) through \(5\). A ball is drawn, replaced, and then a second ball is drawn. Find the probability that the sum of the two numbers is greater than \(8\).

Hints

- Organize the ordered pairs from labels \(1\) through \(5\). - Identify only pairs whose sum is greater than \(8\). - Divide the favorable count by all \(25\) equally likely pairs.

Solution

1. There are \(5\cdot5=25\) equally likely ordered pairs. 2. The pairs with a sum greater than \(8\) are \((4,5),(5,4),(5,5)\). 3. Therefore, the probability is \(\frac{3}{25}=12\%\).

Answer

\(\frac{3}{25}=12\%\)
Sample spaces for compound events 14
A fair coin is flipped twice. Write the sample space and find the probability of getting exactly one head.
Figure for problem 537493

Hints

- List all ordered outcomes systematically. - Which outcomes contain exactly one H?

Solution

1. The sample space is \(S = \{\mathrm{HH}, \mathrm{HT}, \mathrm{TH}, \mathrm{TT}\}\). 2. The favorable outcomes are \(\mathrm{HT}\) and \(\mathrm{TH}\). 3. Therefore, \(P(\text{exactly one head}) = \frac{2}{4} = \frac{1}{2}\).

Answer

\(S = \{\mathrm{HH}, \mathrm{HT}, \mathrm{TH}, \mathrm{TT}\}\); the probability is \(\frac{1}{2}\).
Sample spaces for compound events 15
A spinner has three equal sections labeled red, blue, and green. After one spin, a fair coin is flipped. What is the probability of the event “blue or tails”?
Figure for problem 537494

Hints

- List all ordered combinations of a color and a coin result. - Do not count the blue-and-tails outcome twice.

Solution

1. There are \(3 \cdot 2 = 6\) equally likely ordered outcomes. 2. The favorable outcomes are \((\text{blue}, \text{heads})\), \((\text{blue}, \text{tails})\), \((\text{red}, \text{tails})\), and \((\text{green}, \text{tails})\). 3. Therefore, \(P(\text{blue or tails}) = \frac{4}{6} = \frac{2}{3}\).

Answer

\(\frac{2}{3}\)
Sample spaces for compound events 16
In \(200\) trials of a two-stage experiment, the frequencies are shown in the tree diagram. Find the relative frequency of event \(B\).
Figure for problem 537506

Hints

- Identify every endpoint in the compound experiment that belongs to event \(B\). - Add those endpoint counts before forming a part-to-whole ratio. - Divide by the total number of trials.

Solution

1. Event \(B\) occurs in the two endpoint categories with counts \(72\) and \(20\), so its total frequency is \(72+20=92\). 2. The relative frequency of \(B\) is \(\frac{92}{200}=0.46\).

Answer

\(0.46=46\%\)
Sample spaces for compound events 17
A random code consists of one letter from \(\{A, B, C\}\) followed by one digit from \(\{1, 2\}\). All six codes are equally likely. Find the probability that the code does not begin with \(A\) and ends in \(2\).
Figure for problem 537511

Hints

- Identify the choices that satisfy each condition. - Count the endpoints that satisfy both conditions.

Solution

1. The six equally likely codes are represented by the six endpoints of the tree. 2. The codes that do not begin with \(A\) and end in \(2\) are \(B2\) and \(C2\), so there are \(2\) favorable outcomes. 3. Therefore, \(P = \frac{2}{6} = \frac{1}{3}\).

Answer

\(\frac{1}{3}\)
Sample spaces for compound events 18
A fair coin is flipped twice. In the tree diagram, H means heads and T means tails. Write a simple event that describes the three selected outcomes, and state its complement.
Figure for problem 537522

Hints

- Find one description shared by all selected outcomes. - Which single outcome is not selected?

Solution

1. The selected outcomes are \(HH\), \(HT\), and \(TH\). 2. A common description is “at least one head.” 3. Its complement is “no heads,” which is the outcome \(TT\).

Answer

Event: at least one head Complement: no heads, or \(TT\)
Sample spaces for compound events 19
A fair four-sided die labeled \(1\) through \(4\) is rolled twice. Find the probability that the second number is greater than the first number.
Figure for problem 537523

Hints

- For each possible first number, list the larger second numbers. - Compare the favorable endpoints with all \(16\) endpoints.

Solution

1. The favorable ordered pairs are \((1, 2)\), \((1, 3)\), \((1, 4)\), \((2, 3)\), \((2, 4)\), and \((3, 4)\). 2. There are \(6\) favorable outcomes among \(4 \cdot 4 = 16\) equally likely ordered outcomes. 3. Therefore, \(P = \frac{6}{16} = \frac{3}{8}\).

Answer

\(\frac{3}{8} = 37.5\%\)
Sample spaces for compound events 20
A morning is described by two conditions: Weather: sunny \(S\) or cloudy \(C\) Train: on time \(O\) or late \(L\) Write the sample space as ordered pairs \((\text{weather}, \text{train})\). Then list the outcomes in which exactly one unfavorable condition occurs, where cloudy and late are unfavorable.

Hints

- Keep the order of the two conditions consistent. - Pair every outcome from the first condition with every outcome from the second. - Check each pair for the exact number of unfavorable conditions.

Solution

1. Pair each weather outcome with each train outcome. 2. The sample space is \(\{(S, O),(S, L),(C, O),(C, L)\}\). 3. Exactly one unfavorable condition occurs in \((S, L)\) and \((C, O)\).

Answer

Sample space: \(\{(S, O),(S, L),(C, O),(C, L)\}\). Exactly one unfavorable condition: \(\{(S, L),(C, O)\}\).
Sample spaces for compound events 21
A device goes through two inspections. At each inspection it either passes \(P\) or fails \(F\). The tree shows the possible paths. Write the sample space as ordered pairs. Then list the outcomes in which the device passes exactly one inspection.
Figure for problem 541795

Hints

- Read each complete path from the first inspection to the second. - Keep the inspection order fixed in each ordered pair. - Count the number of passes in every outcome.

Solution

1. Following every path gives the sample space \(\{(P, P),(P, F),(F, P),(F, F)\}\). 2. Exactly one pass occurs in \((P, F)\) and \((F, P)\).

Answer

Sample space: \(\{(P, P),(P, F),(F, P),(F, F)\}\). Exactly one pass: \(\{(P, F),(F, P)\}\).
Sample spaces for compound events 22
A drone flight is described by an altitude and a direction. Altitude: low \(L\) or high \(H\) Direction: north \(N\), east \(E\), or south \(S\) Write the sample space as ordered pairs \((\text{altitude}, \text{direction})\). Then list the outcomes for the event “high altitude or east.”

Hints

- Pair every first-category outcome with every second-category outcome. - Interpret “or” as including outcomes that satisfy either condition. - Check that no qualifying ordered pair is omitted.

Solution

1. Pair each altitude with each direction. 2. The sample space is \(\{(L, N),(L, E),(L, S),(H, N),(H, E),(H, S)\}\). 3. “High altitude or east” includes all high-altitude outcomes and the low-east outcome. 4. The event is \(\{(L, E),(H, N),(H, E),(H, S)\}\).

Answer

Sample space: \(\{(L, N),(L, E),(L, S),(H, N),(H, E),(H, S)\}\). High altitude or east: \(\{(L, E),(H, N),(H, E),(H, S)\}\).
Sample spaces for compound events 23
A two-letter signal is formed from \(A\), \(B\), and \(C\) without repeating a letter. Write the sample space. Then list the signals whose letters are in alphabetical order.

Hints

- Choose each possible first letter and pair it with the remaining letters. - Preserve the order of the letters in each outcome. - Compare the position of the first letter with the second.

Solution

1. Starting with \(A\) gives \(AB\) and \(AC\). 2. Starting with \(B\) gives \(BA\) and \(BC\). 3. Starting with \(C\) gives \(CA\) and \(CB\). 4. The sample space is \(\{AB,AC,BA,BC,CA,CB\}\). 5. The alphabetically ordered signals are \(AB,\ AC,\ BC\).

Answer

Sample space: \(\{AB,AC,BA,BC,CA,CB\}\). Alphabetical order: \(\{AB,AC,BC\}\).
Sample spaces for compound events 24
At each of two intersections, a robot turns left \((L)\), goes straight \((S)\), or turns right \((R)\). Write the sample space of two-move sequences. Then list the outcomes in which the robot makes the same choice at both intersections.

Hints

- Fix the first move and pair it with every possible second move. - Preserve the order of the two intersections. - Compare the two symbols in each completed outcome.

Solution

1. Starting with \(L\) gives \(LL,\ LS,\ LR\). 2. Starting with \(S\) gives \(SL,\ SS,\ SR\). 3. Starting with \(R\) gives \(RL,\ RS,\ RR\). 4. The sample space is \(\{LL,LS,LR,SL,SS,SR,RL,RS,RR\}\). 5. The same choice occurs twice in \(LL,\ SS,\ RR\).

Answer

Sample space: \(\{LL,LS,LR,SL,SS,SR,RL,RS,RR\}\). Same choice twice: \(\{LL,SS,RR\}\).
Sample spaces for compound events 25
Spinner A has \(2\) equal sections labeled \(1\) and \(2\). Spinner B has \(3\) equal sections labeled \(1\), \(2\), and \(3\). Each spinner is spun once. Complete the two missing entries in the sample-space table, then find the probability that the sum of the two results is \(4\). <table> <tr> <th>Spinner A</th> <th>\(1\)</th> <th>\(2\)</th> <th>\(3\)</th> </tr> <tr> <td>\(1\)</td> <td>\((1, 1)\)</td> <td>\((1, 2)\)</td> <td>?</td> </tr> <tr> <td>\(2\)</td> <td>\((2, 1)\)</td> <td>?</td> <td>\((2, 3)\)</td> </tr> </table>

Hints

- Each row fixes Spinner A's result, and each column fixes Spinner B's result. - Write an ordered pair using the row value first and the column value second. - After completing the table, identify every pair whose coordinates add to \(4\).

Solution

1. The missing entry in row \(1\), column \(3\) is \((1, 3)\). 2. The missing entry in row \(2\), column \(2\) is \((2, 2)\). 3. The table contains \(2\cdot3=6\) equally likely outcomes. 4. The outcomes with sum \(4\) are \((1, 3)\) and \((2, 2)\), so the probability is \(\frac{2}{6}=\frac{1}{3}\).

Answer

Missing entries: \((1, 3)\) and \((2, 2)\) Probability of a sum of \(4\): \(\frac{1}{3}\)
Sample spaces for compound events 26
A fair spinner has three equal regions labeled 1, 2, and 3. It is spun once, and a fair coin is flipped once. Finish the missing row of the two-way table. Then list the outcomes that show an even number **or** heads (including both), and find their probability. <table> <tr><th></th><th>Heads</th><th>Tails</th></tr> <tr><th>1</th><td>1H</td><td>1T</td></tr> <tr><th>2</th><td>?</td><td>?</td></tr> <tr><th>3</th><td>3H</td><td>3T</td></tr> </table>

Hints

- What information does a row label give? What does a column label give? - Mark the cells that qualify before making your list. - Check your final list against the table: have you missed a pair or written one twice?

Solution

1. Row 2 is 2H, 2T, pairing the spinner's 2 with each coin outcome. 2. The table contains six equally likely outcomes. 3. The pairs with an even number or heads are 1H, 2H, 2T, and 3H. 4. Four of the six pairs work, so the probability is \(\frac{4}{6}=\frac{2}{3}\).

Answer

Missing cells: 2H, 2T. Favorable pairs: 1H, 2H, 2T, 3H. Probability: \(\frac{2}{3}\).
Sample spaces for compound events 27
A game draws a colored ball from a bag, then flips a coin. The tree gives the chances for each step. Find the probability of drawing blue and then flipping tails.
Figure for problem 559747

Hints

- What makes a complete result in this two-step game? - Which first-stage branch could lead to the requested result? - How are the chances written on consecutive branches related to the chance of the full path?

Solution

1. The probability of blue is \(\frac{2}{3}\). 2. After either ball color, the chance of tails is \(\frac{1}{2}\). 3. Multiply along the blue-then-tails path: \(\frac{2}{3}\cdot\frac{1}{2}=\frac{1}{3}\).

Answer

\(\frac{1}{3}\).
Sample spaces for compound events 28
A bag has two red beads and one blue bead. Two beads are drawn in order without putting the first one back. Which ordered color results are possible? Explain why one color pair cannot happen.

Hints

- Can a color appear twice if the bag holds only one bead of that color? - The order of the two draws matters.

Solution

1. Two red beads can be drawn, so RR is possible. 2. Either a red bead then the blue bead (RB), or the blue bead then a red bead (BR), is possible. 3. BB is impossible because the bag has only one blue bead and the first bead is not replaced.

Answer

RR, RB, and BR are possible. BB is impossible because there is only one blue bead.
Sample spaces for compound events 29
At a park, visitors choose a canoe or a guided hike. Canoe riders choose the lake loop or the river loop. Hikers choose the forest, ridge, or waterfall trail. Someone says there are \(2\cdot5=10\) trips because there are two activities and five route choices in all. Explain the mistake and find the correct number of trips.

Hints

- What choices make one complete visit to the park? - Does every second-stage route belong to both first-stage activities?

Solution

1. The two water routes apply only to canoe riders. 2. The three trails apply only to hikers. 3. The number of complete trips is \(2+3=5\), not \(2\cdot5\).

Answer

There are \(5\) trips: \(2\) canoe routes and \(3\) hiking trails. The route choices are not available for both activities.
Sample spaces for compound events 30
Two fair six-sided number cubes are rolled. Consider two ways to record the result. a) The result is the sum of the two numbers. Are the possible sums equally likely? Justify your answer by comparing the probabilities of sums \(2\) and \(7\). b) The result is the ordered pair \((x, y)\), where \(x\) is the result on the first number cube and \(y\) is the result on the second. Explain why the ordered pairs are equally likely, and state the number of outcomes in the sample space \(S\).

Hints

- Count the ordered pairs that produce each sum. - A \(6 \times 6\) outcome grid contains all ordered pairs. - Distinguish between a sum and the ordered pair that produces it.

Solution

1. a) A sum of \(2\) occurs only with \((1, 1)\), so \(P(2) = \frac{1}{36}\). A sum of \(7\) occurs with \((1, 6)\), \((2, 5)\), \((3, 4)\), \((4, 3)\), \((5, 2)\), and \((6, 1)\), so \(P(7) = \frac{6}{36} = \frac{1}{6}\). The sums are not equally likely. 2. b) Each ordered pair combines one of \(6\) results on the first cube with one of \(6\) results on the second. There are \(6 \cdot 6 = 36\) ordered pairs. 3. A \(6 \times 6\) outcome grid has one cell for each ordered pair, and the fair number cubes make these \(36\) cells equally likely. Therefore, each ordered pair has probability \(\frac{1}{36}\).

Answer

a) No. \(P(2) = \frac{1}{36}\), while \(P(7) = \frac{6}{36} = \frac{1}{6}\). b) Yes. There are \(36\) ordered pairs, and each has probability \(\frac{1}{36}\).
Sample spaces for compound events 31
The spinner shown has \(10\) equal sections. The spinner is spun twice. a) Find the probability of the ordered result \((\text{blue}, \text{blue})\). b) Ji-ho says, “There are four possible color combinations: \((\text{blue}, \text{blue})\), \((\text{blue}, \text{yellow})\), \((\text{yellow}, \text{blue})\), and \((\text{yellow}, \text{yellow})\). Therefore, each combination has probability \(25\%\).” Explain why this reasoning is incorrect.
Figure for problem 513660

Hints

- Use the spinner to compare the single-spin probabilities of blue and yellow. - For two spins, think of equally likely ordered section pairs rather than only the four color labels. - Ask whether each color combination contains the same number of those equally likely pairs.

Solution

1. Each spin can land on one of \(10\) equal sections, so a \(10 \times 10\) outcome grid has \(100\) equally likely ordered section pairs. 2. There are \(7\) blue choices on the first spin and \(7\) blue choices on the second, giving \(7 \cdot 7 = 49\) blue-blue section pairs. Therefore, \(P(\text{blue}, \text{blue}) = \frac{49}{100} = 0.49 = 49\%\). 3. The four color combinations group different numbers of equally likely section pairs. Blue-blue has \(49\) pairs, blue-yellow has \(7 \cdot 3 = 21\), yellow-blue has \(3 \cdot 7 = 21\), and yellow-yellow has \(3 \cdot 3 = 9\). Therefore, the four color combinations are not equally likely.

Answer

a) \(0.49 = 49\%\) b) The four combinations are not equally likely because blue and yellow are not equally likely on a single spin.
Sample spaces for compound events 32
An opaque bag contains \(10\) balls that are either black or white. To estimate the composition, a ball is drawn, its color is recorded, and the ball is replaced. In \(200\) draws, black appears \(124\) times and white appears \(76\) times. a) Based on the results, estimate the number of black balls in the bag. Explain your estimate. b) Suppose the bag actually contains \(6\) black balls and \(4\) white balls. If two balls are drawn with replacement, what is the theoretical probability of drawing exactly one black ball and one white ball?

Hints

- Use the experimental proportion of black balls to estimate the proportion in the bag. - Scale the estimated proportion to a total of \(10\) balls. - For part b, include both possible color orders.

Solution

1. a) The relative frequency of black is \(\frac{124}{200} = 0.62\). 2. Multiplying this estimated proportion by the \(10\) balls gives \(10 \cdot 0.62 = 6.2\). Because the number of balls must be a whole number, a reasonable estimate is \(6\) black balls. 3. b) With replacement, there are \(10 \cdot 10 = 100\) equally likely ordered pairs of ball draws. 4. Black then white can occur in \(6 \cdot 4 = 24\) ordered outcomes, and white then black can occur in \(4 \cdot 6 = 24\) ordered outcomes. Thus there are \(48\) favorable outcomes, so \(P = \frac{48}{100} = 0.48\).

Answer

a) About \(6\) black balls b) \(0.48 = 48\%\)
Sample spaces for compound events 33
A three-digit number is formed by independently choosing either \(1\) or \(2\), with equal probability, for each digit. 1. List every outcome in the sample space \(S\). 2. Event \(G\) is: “The number contains the digit \(1\) at least twice.” Write the set \(G\). 3. Describe the complement \(\overline{G}\) in words and write its set of outcomes. 4. Find \(P(G)\) and \(P(\overline{G})\), and show that their sum is \(1\).

Hints

- How many choices are available for each digit? Use an organized list or tree diagram. - What is the logical opposite of “at least twice”? - Recall the relationship between the probability of an event and the probability of its complement.

Solution

1. Listing the choices systematically gives \(S = \{111, 112, 121, 122, 211, 212, 221, 222\}\), so \(|S| = 8\). 2. The outcomes containing two or three digits equal to \(1\) are \(G = \{111, 112, 121, 211\}\). 3. The complement means the number contains the digit \(1\) at most once. Therefore, \(\overline{G} = \{122, 212, 221, 222\}\). 4. Each outcome is equally likely, so \(P(G) = \frac{4}{8} = \frac{1}{2} = 0.5\) and \(P(\overline{G}) = \frac{4}{8} = \frac{1}{2} = 0.5\). Their sum is \(0.5 + 0.5 = 1\).

Answer

1. \(S = \{111, 112, 121, 122, 211, 212, 221, 222\}\) 2. \(G = \{111, 112, 121, 211\}\) 3. \(\overline{G}\): The number contains the digit \(1\) at most once. \(\overline{G} = \{122, 212, 221, 222\}\) 4. \(P(G) = 0.5\), \(P(\overline{G}) = 0.5\), and \(0.5 + 0.5 = 1\).
Sample spaces for compound events 34
A two-digit number is formed from the digit cards \(\{1, 2, 3, 4, 5\}\). a) First, each card is replaced after it is drawn, so repeated digits such as \(22\) are possible. Find the probability that the number contains at least one \(5\). b) Now the cards are drawn without replacement. Find the probability that the number contains at least one \(5\). c) Compare the answers. In which case is the probability greater? Briefly explain.

Hints

- Use the complement by counting numbers with no \(5\). - Track how many cards remain on the second draw. - Compare the two probabilities after calculating them.

Solution

1. a) With replacement, there are \(5 \cdot 5 = 25\) two-digit outcomes. There are \(4 \cdot 4 = 16\) outcomes with no \(5\). Therefore, \(P(\text{at least one 5}) = \frac{25 - 16}{25} = \frac{9}{25} = 0.36\). 2. b) Without replacement, there are \(5 \cdot 4 = 20\) outcomes. There are \(4 \cdot 3 = 12\) outcomes with no \(5\). Therefore, \(P(\text{at least one 5}) = \frac{20 - 12}{20} = \frac{2}{5} = 0.4\). 3. c) The probability is greater without replacement. If the first digit is not \(5\), the chance of drawing \(5\) second increases from \(\frac{1}{5}\) to \(\frac{1}{4}\).

Answer

a) \(\frac{9}{25} = 36\%\) b) \(\frac{2}{5} = 40\%\) c) The probability is greater without replacement.
Sample spaces for compound events 35
A spinner has three equal sections labeled \(1\), \(2\), and \(3\). It is spun three times. a) List the ordered triples in each event: \(A\): A \(1\) occurs only on the first spin. \(B\): The first \(1\) occurs on the third spin. b) Find the number of outcomes in each event: \(C\): The third spin is \(1\). \(D\): The third spin is not \(1\). c) Find \(P(A)\), \(P(B)\), \(P(C)\), and \(P(D)\).

Hints

- Translate each event into conditions on the first, second, and third entries. - “Only on the first spin” excludes \(1\) from the other positions. - “First occurs on the third spin” excludes \(1\) from the first two positions. - Use the fundamental counting principle to count outcomes. - All \(27\) ordered triples are equally likely.

Solution

1. For event \(A\), the first entry is \(1\), and the other entries are \(2\) or \(3\). Thus, \(A=\{(1, 2, 2),(1, 2, 3),(1, 3, 2),(1, 3, 3)\}\). 2. For event \(B\), the first two entries are \(2\) or \(3\), and the third entry is \(1\). Thus, \(B=\{(2, 2, 1),(2, 3, 1),(3, 2, 1),(3, 3, 1)\}\). 3. In event \(C\), the first two spins each have \(3\) choices and the third is fixed, so there are \(3\cdot 3=9\) outcomes. In event \(D\), the third spin has \(2\) choices, so there are \(3\cdot 3\cdot 2=18\) outcomes. 4. There are \(3^3=27\) equally likely outcomes. Therefore, \(P(A)=\frac{4}{27}\), \(P(B)=\frac{4}{27}\), \(P(C)=\frac{9}{27}=\frac{1}{3}\), and \(P(D)=\frac{18}{27}=\frac{2}{3}\).

Answer

a) \(A=\{(1, 2, 2),(1, 2, 3),(1, 3, 2),(1, 3, 3)\}\); \(B=\{(2, 2, 1),(2, 3, 1),(3, 2, 1),(3, 3, 1)\}\) b) \(C\): \(9\) outcomes; \(D\): \(18\) outcomes c) \(P(A)=\frac{4}{27}\); \(P(B)=\frac{4}{27}\); \(P(C)=\frac{1}{3}\); \(P(D)=\frac{2}{3}\)
Sample spaces for compound events 36
An urn contains four balls labeled \(1\), \(2\), \(3\), and \(4\). Two draws are made with replacement. Find the probability that: a) The sum of the two numbers is exactly \(5\). b) The product of the two numbers is a perfect square. c) The first number is greater than the second number.

Hints

- Use the fundamental counting principle to find the total number of ordered pairs. - Make a table or list of all \(16\) outcomes. - Include equal factors such as \(2\cdot 2\) when checking perfect-square products. - List ordered pairs systematically.

Solution

1. There are \(4\cdot 4=16\) equally likely ordered outcomes. 2. The outcomes with sum \(5\) are \((1, 4)\), \((2, 3)\), \((3, 2)\), and \((4, 1)\). Thus, the probability is \(\frac{4}{16}=\frac{1}{4}\). 3. The outcomes with a perfect-square product are \((1, 1)\), \((1, 4)\), \((2, 2)\), \((3, 3)\), \((4, 1)\), and \((4, 4)\). Thus, the probability is \(\frac{6}{16}=\frac{3}{8}\). 4. The outcomes with the first number greater are \((2, 1)\), \((3, 1)\), \((3, 2)\), \((4, 1)\), \((4, 2)\), and \((4, 3)\). Thus, the probability is \(\frac{6}{16}=\frac{3}{8}\).

Answer

a) \(\frac{1}{4}=0.25\) b) \(\frac{3}{8}=0.375\) c) \(\frac{3}{8}=0.375\)
Sample spaces for compound events 37
Two fair six-sided dice are rolled, and their sum \(S\) is recorded. a) Find the probability that \(S\le 4\) or \(S\ge 10\). b) Let \(E\) be the event \(3<S<11\). Find the probability of \(E^c\).

Hints

- List the number of ordered outcomes that produce each possible sum. - Translate “greater than \(3\) and less than \(11\)” into an inequality. - The endpoints are included in “at most” and “at least.” - An event and its complement have probabilities that add to \(1\).

Solution

1. The \(6\times 6\) sample space has \(36\) equally likely ordered outcomes. 2. For \(S\le 4\), the numbers of outcomes for sums \(2\), \(3\), and \(4\) are \(1\), \(2\), and \(3\), for a total of \(6\). For \(S\ge 10\), the counts for sums \(10\), \(11\), and \(12\) are \(3\), \(2\), and \(1\), also totaling \(6\). The two events are disjoint, so the probability is \(\frac{12}{36}=\frac{1}{3}\). 3. The complement of \(3<S<11\) is \(S\le 3\) or \(S\ge 11\). These sums have \(1+2+2+1=6\) outcomes, so \(P(E^c)=\frac{6}{36}=\frac{1}{6}\).

Answer

a) \(\frac{1}{3}\) b) \(P(E^c)=\frac{1}{6}\)
Sample spaces for compound events 38
Spinners A and B are shown. Spinner A has \(5\) equal sections, and Spinner B has \(4\) equal sections. Each spinner is spun once. Find the probability that: a) Both spinners land on the same color. b) The sum of the two numbers is at least \(6\). Give each probability as a simplified fraction and a percent.
Figure for problem 531995

Hints

- Read each spinner's color-number sections from the image. - Treat a result as an ordered pair, one section from A and one from B. - For part b, list or organize the number pairs meeting the sum condition.

Solution

1. There are \(5\cdot4=20\) equally likely ordered section pairs. 2. For matching colors, there are \(2\cdot1=2\) red-red pairs and \(2\cdot2=4\) blue-blue pairs. Thus, \(P(\text{same color})=\frac{6}{20}=\frac{3}{10}=30\%\). 3. The number pairs with sum at least \(6\) are \((2,4),(3,3),(3,4),(4,2),(4,3),(4,4),(5,1),(5,2),(5,3),(5,4)\). Therefore, \(P(\text{sum}\ge6)=\frac{10}{20}=\frac{1}{2}=50\%\).

Answer

a) \(\frac{3}{10}=30\%\) b) \(\frac{1}{2}=50\%\)
Sample spaces for compound events 39
Spin twice. All sections are equal in size. Find each probability as a fraction in simplest form. a) The same number occurs on both spins. b) The sum of the two numbers is greater than \(4\). c) The first spin lands on red and the second spin lands on blue.
Figure for problem 532005

Hints

- Read how often each number and color appears on the spinner. - Treat the two spins as ordered outcomes. - Repeated labels create multiple equally likely section pairs for the same numerical pair.

Solution

1. There are \(6\cdot6=36\) equally likely ordered section pairs. 2. The number \(1\) appears on \(2\) sections, \(2\) on \(3\), and \(3\) on \(1\). Thus, \(P(\text{same number})=\frac{2^2+3^2+1^2}{36}=\frac{14}{36}=\frac{7}{18}\). 3. A sum greater than \(4\) comes from number pairs \((2,3),(3,2),(3,3)\). Accounting for repeated labels gives \(3\cdot1+1\cdot3+1\cdot1=7\) favorable section pairs, so the probability is \(\frac{7}{36}\). 4. There are \(2\) red sections and \(2\) blue sections, so \(P(\text{red then blue})=\frac{2}{6}\cdot\frac{2}{6}=\frac{1}{9}\).

Answer

a) \(\frac{7}{18}\) b) \(\frac{7}{36}\) c) \(\frac{1}{9}\)
Sample spaces for compound events 40
Spinners A and B are shown. Spinner A has \(4\) equal sections, and Spinner B has \(6\) equal sections. Each spinner is spun once. Find each probability as a simplified fraction. a) Both spinners land on red sections. b) The sum of the two numbers is exactly \(6\).
Figure for problem 532012

Hints

- Read the color-number sections from both spinners. - Count all ordered section pairs before counting favorable ones. - For the sum event, organize the ordered number pairs that total \(6\).

Solution

1. There are \(4\cdot6=24\) equally likely ordered section pairs. 2. Spinner A has \(1\) red section and Spinner B has \(3\), so \(P(\text{both red})=\frac{1}{4}\cdot\frac{3}{6}=\frac{1}{8}\). 3. The number pairs with sum \(6\) are \((1,5),(2,4),(3,3),(4,2)\), giving \(P(\text{sum}=6)=\frac{4}{24}=\frac{1}{6}\).

Answer

a) \(\frac{1}{8}\) b) \(\frac{1}{6}\)
Sample spaces for compound events 41
An urn contains four balls labeled \(3\), \(5\), \(7\), and \(9\). Three balls are drawn in order without replacement. The labels form the hundreds, tens, and ones digits of a three-digit number. Find the probability of each event. a) The number is greater than \(700\). b) The sum of the digits is exactly \(15\). c) The number is even.

Hints

- Treat the three draws as an ordered sample space without replacement. - For part a, focus on which labels can occupy the hundreds place. - For part b, identify the required set of digits before counting its orders.

Solution

1. There are \(4\cdot3\cdot2=24\) equally likely ordered outcomes. 2. For part a, the hundreds digit must be \(7\) or \(9\). Each choice allows \(3\cdot2=6\) arrangements of the remaining digits, so the probability is \(\frac{12}{24}=\frac{1}{2}\). 3. For part b, only the digits \(3,5,7\) have sum \(15\). They can be arranged in \(3\cdot2\cdot1=6\) orders, so the probability is \(\frac{6}{24}=\frac{1}{4}\). 4. Every available digit is odd, so every possible number is odd. The probability of an even number is \(0\).

Answer

a) \(\frac{1}{2}=50\%\) b) \(\frac{1}{4}=25\%\) c) \(0=0\%\)
Sample spaces for compound events 42
A spinner has six equal sections labeled and colored as shown. It is spun twice. Find the probability that the sum of the two numbers is at least \(6\). Give the answer as a simplified fraction.
Figure for problem 532042

Hints

- Count how many sections carry each number. - List the ordered number pairs with sum at least \(6\). - Account for repeated labels by counting section pairs. - Simplify the final fraction.

Solution

1. The possible numbers and their probabilities are \(P(1)=\frac{1}{6}\), \(P(2)=\frac{1}{6}\), \(P(3)=\frac{2}{6}\), and \(P(5)=\frac{2}{6}\). 2. The number pairs with sum at least \(6\) are \((1, 5)\), \((2, 5)\), \((3, 3)\), \((3, 5)\), \((5, 1)\), \((5, 2)\), \((5, 3)\), and \((5, 5)\). 3. Counting the corresponding section pairs gives \(2+2+4+4+2+2+4+4=24\) favorable outcomes out of \(36\). 4. Therefore, the probability is \(\frac{24}{36}=\frac{2}{3}\).

Answer

\(\frac{2}{3}\)
Sample spaces for compound events 43
The spinner shown has \(8\) equal colored sections. It is spun twice. Find each probability as a simplified fraction and a percent. a) Both spins are the same color. b) Green occurs at least once. c) The first spin is red and the second spin is blue.
Figure for problem 532053

Hints

- Count each color directly from the spinner to get the one-spin probabilities. - For matching colors, consider each possible matching-color path. - For “at least one,” consider whether a complement is easier to count.

Solution

1. From the spinner, \(P(\text{red})=\frac{3}{8}\), \(P(\text{blue})=\frac{4}{8}\), and \(P(\text{green})=\frac{1}{8}\). 2. \(P(\text{same color})=\left(\frac{3}{8}\right)^2+\left(\frac{4}{8}\right)^2+\left(\frac{1}{8}\right)^2=\frac{13}{32}=40.625\%\). 3. \(P(\text{at least one green})=1-\left(\frac{7}{8}\right)^2=\frac{15}{64}=23.4375\%\). 4. \(P(\text{red then blue})=\frac{3}{8}\cdot\frac{4}{8}=\frac{3}{16}=18.75\%\).

Answer

a) \(\frac{13}{32}=40.625\%\) b) \(\frac{15}{64}=23.4375\%\) c) \(\frac{3}{16}=18.75\%\)
Sample spaces for compound events 44
The spinner shown has \(5\) equal colored sections. It is spun twice. Find each probability as a simplified fraction and a percent. a) The first spin is green and the second spin is yellow. b) Red occurs at least once.
Figure for problem 532088

Hints

- Read the one-spin color probabilities from the spinner. - Part a specifies an order, so treat the two spins as ordered. - For part b, compare “at least one red” with its complement.

Solution

1. From the spinner, \(P(\text{green})=\frac{2}{5}\), \(P(\text{red})=\frac{2}{5}\), and \(P(\text{yellow})=\frac{1}{5}\). 2. \(P(\text{green then yellow})=\frac{2}{5}\cdot\frac{1}{5}=\frac{2}{25}=8\%\). 3. \(P(\text{at least one red})=1-\left(\frac{3}{5}\right)^2=\frac{16}{25}=64\%\).

Answer

a) \(\frac{2}{25}=8\%\) b) \(\frac{16}{25}=64\%\)
Sample spaces for compound events 45
The spinner shown has \(8\) equal colored sections. It is spun twice. Find the probability that: a) Both spins are the same color. b) Yellow occurs at least once.
Figure for problem 532127

Hints

- Count the color frequencies on the spinner first. - For part a, add the probabilities of the three matching-color cases. - For part b, use the complement of getting no yellow on either spin.

Solution

1. From the spinner, \(P(\text{red})=\frac{1}{2}\), \(P(\text{green})=\frac{1}{4}\), and \(P(\text{yellow})=\frac{1}{4}\). 2. \(P(\text{same color})=\left(\frac{1}{2}\right)^2+\left(\frac{1}{4}\right)^2+\left(\frac{1}{4}\right)^2=\frac{3}{8}=37.5\%\). 3. \(P(\text{at least one yellow})=1-\left(\frac{3}{4}\right)^2=\frac{7}{16}=43.75\%\).

Answer

a) \(\frac{3}{8}=37.5\%\) b) \(\frac{7}{16}=43.75\%\)
Sample spaces for compound events 46
The spinner shown has \(5\) equal color-number sections. It is spun twice. a) Find the probability that the sum of the two numbers is at least \(7\). b) Find the probability that the two spins land on different colors.
Figure for problem 532142

Hints

- Read the number and color of each equal section from the spinner. - Organize the ordered number pairs systematically for part a. - For different colors, consider counting the same-color complement.

Solution

1. There are \(5\cdot5=25\) equally likely ordered outcomes. 2. The number pairs with sum at least \(7\) are \((2,5),(3,4),(3,5),(4,3),(4,4),(4,5),(5,2),(5,3),(5,4),(5,5)\), so the probability is \(\frac{10}{25}=\frac{2}{5}=40\%\). 3. For the complement in part b, there are \(4\) red-red outcomes, \(4\) blue-blue outcomes, and \(1\) green-green outcome, so \(P(\text{same color})=\frac{9}{25}\). 4. Therefore, \(P(\text{different colors})=1-\frac{9}{25}=\frac{16}{25}=64\%\).

Answer

a) \(\frac{2}{5}=40\%\) b) \(\frac{16}{25}=64\%\)
Sample spaces for compound events 47
The spinner shown has six equal sections and is spun twice. Find the probability of each event. a) Both spins land on the same color. b) The spinner lands on red at least once. c) The first spin is green and the second spin is blue.
Figure for problem 532146

Hints

- Find the probability of each color on one spin. - For part a, add the probabilities of the three matching-color outcomes. - For part b, use the complement of no red. - For part c, multiply the probabilities in the stated order. - Simplify each fraction.

Solution

1. The one-spin probabilities are \(P(\text{green})=\frac{3}{6}=\frac{1}{2}\), \(P(\text{blue})=\frac{2}{6}=\frac{1}{3}\), and \(P(\text{red})=\frac{1}{6}\). 2. The matching-color outcomes are green-green, blue-blue, and red-red: \(P(\text{same color})=\left(\frac{1}{2}\right)^2+\left(\frac{1}{3}\right)^2+\left(\frac{1}{6}\right)^2=\frac{1}{4}+\frac{1}{9}+\frac{1}{36}=\frac{7}{18}\). 3. Use the complement of no red: \(P(\text{at least one red})=1-\left(\frac{5}{6}\right)^2=1-\frac{25}{36}=\frac{11}{36}\). 4. For the specified order, multiply the probabilities: \(P(\text{green then blue})=\frac{1}{2}\cdot\frac{1}{3}=\frac{1}{6}\).

Answer

a) \(\frac{7}{18}\) b) \(\frac{11}{36}\) c) \(\frac{1}{6}\)
Sample spaces for compound events 48
Spinner A has three equal sections labeled \(1\), \(2\), and \(3\). Spinner B has four equal sections labeled \(1\), \(2\), \(3\), and \(4\). Each spinner is spun once. Find the probability of each event. a) The sum of the two numbers is \(5\). b) The number on Spinner B is greater than the number on Spinner A. c) Both spinners show the same number.

Hints

- Treat each result as an ordered pair from the two stated number sets. - List the pairs satisfying each condition. - Divide each favorable count by the \(12\) equally likely pairs.

Solution

1. There are \(3\cdot4=12\) equally likely ordered pairs \((a,b)\). 2. The pairs with sum \(5\) are \((1,4),(2,3),(3,2)\), so the probability is \(\frac{3}{12}=\frac{1}{4}\). 3. The pairs with \(b>a\) are \((1,2),(1,3),(1,4),(2,3),(2,4),(3,4)\), so the probability is \(\frac{6}{12}=\frac{1}{2}\). 4. The matching pairs are \((1,1),(2,2),(3,3)\), so the probability is \(\frac{3}{12}=\frac{1}{4}\).

Answer

a) \(\frac{1}{4}\) b) \(\frac{1}{2}\) c) \(\frac{1}{4}\)
Sample spaces for compound events 49
The spinner shown has \(4\) equal colored sections. It is spun three times. Event \(E\) is “exactly one spin lands on yellow.” a) List all outcomes in event \(E\). Use B for blue and Y for yellow. b) Find \(P(E)\) as a simplified fraction.
Figure for problem 532152

Hints

- Read the one-spin blue and yellow probabilities from the spinner. - Place the single yellow in each possible position among the three spins. - Multiply along one favorable sequence, then account for all favorable positions.

Solution

1. Exactly one yellow can occur in the first, second, or third position, giving \((Y,B,B),(B,Y,B),(B,B,Y)\). 2. From the spinner, \(P(Y)=\frac{1}{4}\) and \(P(B)=\frac{3}{4}\). 3. Each favorable sequence has probability \(\frac{1}{4}\cdot\frac{3}{4}\cdot\frac{3}{4}=\frac{9}{64}\). 4. Therefore, \(P(E)=3\cdot\frac{9}{64}=\frac{27}{64}\).

Answer

a) \((Y,B,B)\), \((B,Y,B)\), and \((B,B,Y)\) b) \(P(E)=\frac{27}{64}\)
Sample spaces for compound events 50
The spinner shown has \(4\) equal colored sections. It is spun three times. Find each probability as a simplified fraction and a decimal. a) The colors occur in the exact order blue, red, yellow. b) The three spins show three different colors.
Figure for problem 532155

Hints

- Read the one-spin color probabilities from the spinner. - For part a, multiply in the exact stated order. - For part b, account for every order in which the three different colors can occur.

Solution

1. From the spinner, \(P(B)=\frac{1}{2}\), \(P(R)=\frac{1}{4}\), and \(P(Y)=\frac{1}{4}\). 2. For the exact order blue, red, yellow, \(P(B,R,Y)=\frac{1}{2}\cdot\frac{1}{4}\cdot\frac{1}{4}=\frac{1}{32}=0.03125\). 3. Three different colors means blue, red, and yellow each occur once. There are \(3\cdot2\cdot1=6\) orders, each with probability \(\frac{1}{32}\), so the probability is \(\frac{3}{16}=0.1875\).

Answer

a) \(\frac{1}{32}=0.03125\) b) \(\frac{3}{16}=0.1875\)
Sample spaces for compound events 51
The spinner shown has \(8\) equal sections labeled \(1\) through \(8\) and colored blue, green, or red. It is spun twice. Let the events be: A: Both numbers are odd. B: The sum of the two numbers is greater than \(12\). C: The first spin is blue and the second spin is red. Find each probability. a) \(P(C)\) b) \(P(A)\) c) \(P(B)\)
Figure for problem 532161

Hints

- Read the color attached to each numbered section from the spinner. - Treat the two spins as ordered outcomes. - For the sum event, list high-number pairs systematically.

Solution

1. The spinner shows \(4\) blue sections and \(2\) red sections, so \(P(C)=\frac{4}{8}\cdot\frac{2}{8}=\frac{1}{8}\). 2. Four of the eight labels are odd, so \(P(A)=\frac{4}{8}\cdot\frac{4}{8}=\frac{1}{4}\). 3. There are \(64\) equally likely ordered number pairs. The pairs with sum greater than \(12\) are \((5,8),(6,7),(6,8),(7,6),(7,7),(7,8),(8,5),(8,6),(8,7),(8,8)\), so \(P(B)=\frac{10}{64}=\frac{5}{32}\).

Answer

a) \(P(C)=\frac{1}{8}\) b) \(P(A)=\frac{1}{4}\) c) \(P(B)=\frac{5}{32}\)
Sample spaces for compound events 52
The \(8\)-section spinner shown is spun twice. Find the probability of each event. a) The same number is spun both times. b) The sum of the two numbers is exactly \(4\). c) The two sections have different colors. d) The number \(1\) is spun at least once.
Figure for problem 535893

Hints

- Read how often each number and color appears on the spinner. - Treat the two spins as ordered section pairs. - For parts c and d, a complement may reduce the counting.

Solution

1. Two spins produce \(8\cdot8=64\) equally likely ordered section pairs. 2. Each of the four numbers appears on two sections. For each number, \(2\cdot2=4\) pairs show that number twice, so part a has \(16\) favorable outcomes and probability \(\frac{1}{4}\). 3. A sum of \(4\) can come from \((1,3),(2,2),(3,1)\). Each numerical pair corresponds to \(4\) section pairs, so part b is \(\frac{12}{64}=\frac{3}{16}\). 4. Each of the four colors has two sections, so there are \(4\cdot4=16\) same-color outcomes. Thus, part c is \(\frac{48}{64}=\frac{3}{4}\). 5. Six sections are not labeled \(1\), so \(36\) ordered pairs contain no \(1\). Thus, part d is \(\frac{64-36}{64}=\frac{7}{16}\).

Answer

a) \(\frac{1}{4}=25\%\) b) \(\frac{3}{16}=18.75\%\) c) \(\frac{3}{4}=75\%\) d) \(\frac{7}{16}=43.75\%\)
Sample spaces for compound events 53
The spinner shown has \(4\) equal sections. It is spun three times. a) Find the probability that the three spins show three different colors. b) Find the probability that exactly two spins land on red.
Figure for problem 535964

Hints

- Read the four equally likely colors from the spinner. - For part a, track how many color choices remain after each distinct color appears. - For part b, consider the possible position of the one spin that is not red.

Solution

1. Each color has probability \(\frac{1}{4}\). 2. For three different colors, the first spin can be any color, the second must be one of the other three, and the third one of the remaining two. Thus, the probability is \(1\cdot\frac{3}{4}\cdot\frac{2}{4}=\frac{3}{8}\). 3. Exactly two red spins can occur in three positions. Each favorable order has probability \(\frac{1}{4}\cdot\frac{1}{4}\cdot\frac{3}{4}=\frac{3}{64}\), so the total is \(3\cdot\frac{3}{64}=\frac{9}{64}\).

Answer

a) \(\frac{3}{8}\) b) \(\frac{9}{64}\)
Sample spaces for compound events 54
The \(8\)-section spinner shown is spun three times. a) Find the probability of event \(E_1\): no spin lands on yellow. b) Find the probability of event \(E_2\): exactly two spins land on red. c) Which event is more likely? Justify your answer by comparing the probabilities.
Figure for problem 535986

Hints

- Read the one-spin color probabilities from the spinner. - For part a, think about the probability of not yellow on all three spins. - For part b, consider the possible positions of the one spin that is not red.

Solution

1. From the spinner, \(P(\text{red})=\frac{1}{2}\), \(P(\text{blue})=\frac{1}{4}\), and \(P(\text{yellow})=\frac{1}{4}\). 2. \(P(E_1)=\left(\frac{3}{4}\right)^3=\frac{27}{64}\). 3. Exactly two red spins can occur in three positions. Since \(P(\text{red})=P(\text{not red})=\frac{1}{2}\), \(P(E_2)=3\cdot\left(\frac{1}{2}\right)^2\cdot\frac{1}{2}=\frac{3}{8}=\frac{24}{64}\). 4. Since \(\frac{27}{64}>\frac{24}{64}\), event \(E_1\) is more likely.

Answer

a) \(P(E_1)=\frac{27}{64}\) b) \(P(E_2)=\frac{3}{8}\) c) Event \(E_1\) is more likely because \(\frac{27}{64}>\frac{24}{64}\).
Sample spaces for compound events 55
The spinner shown has five equal sections and is spun twice. The two numbers are added. Find the probability that the sum is exactly \(4\).
Figure for problem 535987

Hints

- Find the probability of each number on one spin. - List the ordered pairs whose sum is \(4\). - Multiply within each ordered pair and add the favorable probabilities.

Solution

1. The number \(1\) appears once, \(2\) appears twice, \(3\) appears once, and \(4\) appears once. Thus, \(P(1)=\frac{1}{5}\), \(P(2)=\frac{2}{5}\), and \(P(3)=\frac{1}{5}\). 2. The ordered pairs with sum \(4\) are \((1, 3)\), \((3, 1)\), and \((2, 2)\). 3. Their probabilities are \(\frac{1}{5}\cdot\frac{1}{5}=\frac{1}{25}\), \(\frac{1}{5}\cdot\frac{1}{5}=\frac{1}{25}\), and \(\frac{2}{5}\cdot\frac{2}{5}=\frac{4}{25}\). 4. Therefore, \(P(\text{sum }4)=\frac{1}{25}+\frac{1}{25}+\frac{4}{25}=\frac{6}{25}=24\%\).

Answer

\(\frac{6}{25}=24\%\)
Sample spaces for compound events 56
A spinner has \(8\) equal sections labeled \(1\) through \(8\). It is spun three times, and each number is recorded. Find the probability of each event. a) Only the first and third numbers are even. b) Only the first number is a perfect square. c) All three numbers are greater than \(5\). d) The same number occurs on all three spins.

Hints

- For each part, identify which of the labels \(1\) through \(8\) are allowed on each spin. - The word “only” requires the other spins not to have the named property. - For the all-same event, count the possible repeated-number triples.

Solution

1. Four of the eight labels are even and four are odd, so part a is \(\frac{4}{8}\cdot\frac{4}{8}\cdot\frac{4}{8}=\frac{1}{8}\). 2. The perfect squares are \(1\) and \(4\), so part b is \(\frac{2}{8}\cdot\frac{6}{8}\cdot\frac{6}{8}=\frac{9}{64}\). 3. The labels greater than \(5\) are \(6,7,8\), so part c is \(\left(\frac{3}{8}\right)^3=\frac{27}{512}\). 4. There are eight matching triples \((1,1,1)\) through \((8,8,8)\), so part d is \(8\cdot\left(\frac{1}{8}\right)^3=\frac{1}{64}\).

Answer

a) \(\frac{1}{8}\) b) \(\frac{9}{64}\) c) \(\frac{27}{512}\) d) \(\frac{1}{64}\)
Sample spaces for compound events 57
The spinner shown has eight equal sections: two blue, three red, and one each green, yellow, and orange. It is spun twice. Find the probability of each event. a) The sum of the two numbers is \(3\). b) The first number is \(1\), and the second number is greater than \(1\). c) Both spins land on the same color.
Figure for problem 536075

Hints

- Find the probability of each number and each color on one spin. - For part a, list the ordered pairs whose sum is \(3\). - For part b, count the sections labeled with a number greater than \(1\). - For part c, add the probabilities of blue-blue, red-red, and the three other matching-color outcomes.

Solution

1. The number probabilities are \(P(1)=\frac{2}{8}=\frac{1}{4}\), \(P(2)=\frac{3}{8}\), and \(P(3)=P(4)=P(5)=\frac{1}{8}\). 2. A sum of \(3\) occurs with \((1, 2)\) or \((2, 1)\). Therefore, \(P(\text{sum }3)=\frac{2}{8}\cdot\frac{3}{8}+\frac{3}{8}\cdot\frac{2}{8}=\frac{3}{16}\). 3. The probability that the first number is \(1\) is \(\frac{2}{8}\). Six of the eight sections have numbers greater than \(1\). Thus, \(P(\text{first }1\text{, second greater than }1)=\frac{2}{8}\cdot\frac{6}{8}=\frac{3}{16}\). 4. Blue appears on two sections, red on three sections, and green, yellow, and orange each on one section. Therefore, \(P(\text{same color})=\left(\frac{2}{8}\right)^2+\left(\frac{3}{8}\right)^2+3\cdot\left(\frac{1}{8}\right)^2=\frac{1}{4}\).

Answer

a) \(\frac{3}{16}\) b) \(\frac{3}{16}\) c) \(\frac{1}{4}\)
Sample spaces for compound events 58
The \(10\)-section spinner shown has equal sections. a) Find the probability of blue, red, and yellow on one spin. b) The spinner is spun twice. Find the probability that both spins land on the same color. c) Inês claims, “The probability of getting yellow at least once in two spins is greater than \(35\%\).” Is Inês correct? Show your calculation.
Figure for problem 536085

Hints

- Read the single-spin probabilities from the equal sections of the spinner. - For matching colors, consider the separate ways the two spins can match. - For “at least once,” decide whether direct cases or the opposite event gives the cleaner calculation.

Solution

1. From the spinner, \(P(\text{blue})=\frac{1}{2}\), \(P(\text{red})=\frac{3}{10}\), and \(P(\text{yellow})=\frac{1}{5}\). 2. \(P(\text{same color})=\left(\frac{1}{2}\right)^2+\left(\frac{3}{10}\right)^2+\left(\frac{1}{5}\right)^2=\frac{19}{50}=38\%\). 3. The probability of no yellow is \(\left(\frac{4}{5}\right)^2\), so \(P(\text{at least one yellow})=1-\left(\frac{4}{5}\right)^2=\frac{9}{25}=36\%\). Inês is correct.

Answer

a) \(P(\text{blue})=\frac{1}{2}\), \(P(\text{red})=\frac{3}{10}\), and \(P(\text{yellow})=\frac{1}{5}\) b) \(\frac{19}{50}=38\%\) c) Yes. The probability is \(\frac{9}{25}=36\%\), which is greater than \(35\%\).
Sample spaces for compound events 59
A spinner is divided into \(5\) equal sections labeled \(1\) through \(5\). It is spun twice. Compare these events: Event \(A\): The sum of the two numbers is exactly \(6\). Event \(B\): The first number is greater than the second number. Which event is more likely? Support your answer by calculating both probabilities.

Hints

- Organize all ordered pairs from \(\{1,2,3,4,5\}\times\{1,2,3,4,5\}\). - Count the pairs meeting the sum condition. - Separately count the pairs in which the first coordinate is greater.

Solution

1. There are \(5\cdot5=25\) equally likely ordered outcomes. 2. Event \(A\) contains \((1,5),(2,4),(3,3),(4,2),(5,1)\), so \(P(A)=\frac{5}{25}=\frac{1}{5}=20\%\). 3. Event \(B\) has \(10\) ordered pairs with the first number greater than the second, so \(P(B)=\frac{10}{25}=\frac{2}{5}=40\%\). 4. Therefore, event \(B\) is more likely.

Answer

Event \(B\) is more likely. \(P(A)=\frac{1}{5}=20\%\), and \(P(B)=\frac{2}{5}=40\%\).
Sample spaces for compound events 60
An urn contains four balls labeled \(2\), \(3\), \(5\), and \(8\). All four balls are drawn in order without replacement, and their digits form a four-digit number. Find the probability of each event. a) The number is even. b) The number is greater than \(5000\). c) The number is prime.

Hints

- Treat the four draws as equally likely ordered arrangements without replacement. - For part a, focus on the last digit; for part b, focus on the first digit. - For part c, use a divisibility test before trying to inspect individual arrangements.

Solution

1. The four distinct digits can be arranged in \(4\cdot3\cdot2\cdot1=24\) equally likely orders. 2. For part a, the last digit must be \(2\) or \(8\). There are \(2\cdot6=12\) favorable outcomes, so the probability is \(\frac{1}{2}\). 3. For part b, the first digit must be \(5\) or \(8\). Again there are \(12\) favorable outcomes, so the probability is \(\frac{1}{2}\). 4. Every possible number has digit sum \(2+3+5+8=18\), so every number is divisible by \(3\). All are greater than \(3\), so none is prime and the probability is \(0\).

Answer

a) \(\frac{1}{2}\) b) \(\frac{1}{2}\) c) \(0\)
Sample spaces for compound events 61
An urn contains \(2\) red balls and \(3\) blue balls. A ball is drawn, replaced, and the urn is mixed before the next draw. This process is repeated three times. Find the probability of drawing exactly two red balls.

Hints

- List the possible positions of the one blue result. - Replacement keeps the red and blue probabilities unchanged on each draw. - Find the probability of one favorable order, then account for all favorable orders.

Solution

1. On each draw, \(P(\text{red})=\frac{2}{5}=0.4\) and \(P(\text{blue})=\frac{3}{5}=0.6\). 2. The favorable ordered outcomes are red-red-blue, red-blue-red, and blue-red-red. 3. Each has probability \(0.4\cdot0.4\cdot0.6=0.096\). 4. Therefore, the total probability is \(3\cdot0.096=0.288\).

Answer

\(0.288\), or \(28.8\%\)
Sample spaces for compound events 62
A basketball player takes three free throws and wants to make exactly two shots. The tree diagram shows the running total of made shots after each attempt. Let \(M\) represent a make and \(X\) represent a miss. a) How many paths result in exactly two makes? Name the paths. b) What running totals after the second shot still allow the player to finish with exactly two makes? c) For each total from part b, state what must happen on the third shot.
Figure for problem 537462

Hints

- Find all final nodes labeled “2 makes.” - Trace those paths backward to the totals after the second shot. - If the player already has two makes, determine what the last result must be. - If the player has only one make, determine what the last result must be.

Solution

1. The paths with exactly two makes are \(MMX\), \(MXM\), and \(XMM\). There are \(3\) paths. 2. After the second shot, the player must have either \(1\) make or \(2\) makes. 3. With \(1\) make after two shots, the third shot must be made. With \(2\) makes after two shots, the third shot must be missed. With \(0\) makes after two shots, the goal is no longer possible.

Answer

a) \(3\) paths: \(MMX\), \(MXM\), and \(XMM\) b) \(1\) make or \(2\) makes c) From \(1\) make, the third shot must be made; from \(2\) makes, the third shot must be missed.
Sample spaces for compound events 63
Four distinct letter tiles spell MATH. Two tiles are drawn in order without replacement. Write the sample space using two-letter outcomes. Then list the outcomes that contain the letter A.

Hints

- Choose a possible first tile and pair it with every remaining tile. - Remember that the second tile cannot match the first. - Scan the completed outcomes for the required letter.

Solution

1. Starting with M gives \(MA,\ MT,\ MH\). 2. Starting with A gives \(AM,\ AT,\ AH\). 3. Starting with T gives \(TM,\ TA,\ TH\). 4. Starting with H gives \(HM,\ HA,\ HT\). 5. The outcomes containing A are \(MA,\ AM,\ AT,\ AH,\ TA,\ HA\).

Answer

Sample space: \(\{MA,MT,MH,AM,AT,AH,TM,TA,TH,HM,HA,HT\}\). Outcomes containing A: \(\{MA,AM,AT,AH,TA,HA\}\).
Sample spaces for compound events 64
A puzzle path begins by choosing Door A, B, or C. Door A leads to buttons \(1\) or \(2\). Door B leads only to button \(3\). Door C leads to buttons \(4\), \(5\), or \(6\). Write the sample space using outcomes such as \(A1\). Then list the outcomes with an even-numbered button.

Hints

- Treat the available second choices separately for each first choice. - Do not assume every door has the same number of branches. - Filter the completed outcomes by the button condition.

Solution

1. Door A gives \(A1\) and \(A2\). 2. Door B gives \(B3\). 3. Door C gives \(C4,\ C5,\ C6\). 4. The sample space is \(\{A1,A2,B3,C4,C5,C6\}\). 5. The outcomes with even-numbered buttons are \(A2,\ C4,\ C6\).

Answer

Sample space: \(\{A1,A2,B3,C4,C5,C6\}\). Even-numbered button: \(\{A2,C4,C6\}\).
Sample spaces for compound events 65
A commute plan records the weather and the travel mode. Weather is sunny \(S\) or rainy \(R\). Travel mode is bus \(B\), bike \(K\), or walk \(W\). On rainy days, biking is not allowed. Write the possible sample space as ordered pairs \((\text{weather}, \text{mode})\). Then list the outcomes that use walking.

Hints

- Start with all pairings, then apply the restriction. - Keep the weather entry first in every ordered pair. - Select the remaining outcomes with the requested travel mode.

Solution

1. In sunny weather, the possible outcomes are \((S, B)\), \((S, K)\), and \((S, W)\). 2. In rainy weather, the possible outcomes are \((R, B)\) and \((R, W)\); \((R, K)\) is excluded. 3. The sample space is \(\{(S, B),(S, K),(S, W),(R, B),(R, W)\}\). 4. The walking outcomes are \((S, W)\) and \((R, W)\).

Answer

Sample space: \(\{(S, B),(S, K),(S, W),(R, B),(R, W)\}\). Walking outcomes: \(\{(S, W),(R, W)\}\).
Sample spaces for compound events 66
Join the letters along a path after Start to name a complete outcome. List all possible complete outcomes. Which ones include R?
Figure for problem 541801

Hints

- Does a leaf name the whole result, or only the last decision on that path? - Can paths with different numbers of letters still be complete outcomes?

Solution

1. Finishing immediately gives \(F\). 2. Continuing and choosing left gives \(CL\). 3. Continuing, choosing right, and then choosing upper or lower gives \(CRU\) and \(CRD\). 4. The terminal sample space is \(\{F,CL,CRU,CRD\}\). 5. The outcomes that include a right choice are \(CRU\) and \(CRD\).

Answer

Terminal sample space: \(\{F,CL,CRU,CRD\}\). Includes a right choice: \(\{CRU,CRD\}\).
Sample spaces for compound events 67
Two spinners each have three equal sections colored red \(R\), yellow \(Y\), and green \(G\). The spinners are spun separately, and the result of one spin does not affect the other. Write the sample space as ordered pairs (first spinner, second spinner). Then find the probability that exactly one spinner lands on green.

Hints

- Pair each possible result of the first spinner with a result of the second. - Count outcomes containing one green result, not two. - Compare that count with the total number of equally likely outcomes.

Solution

1. The sample space is \(\{(R, R),(R, Y),(R, G),(Y, R),(Y, Y),(Y, G),(G, R),(G, Y),(G, G)\}\). 2. Exactly one green occurs in \((R, G),(Y, G),(G, R),(G, Y)\). 3. There are \(4\) favorable outcomes out of \(9\) equally likely outcomes. 4. The probability is \(\frac{4}{9}\).

Answer

Sample space: \(\{(R, R),(R, Y),(R, G),(Y, R),(Y, Y),(Y, G),(G, R),(G, Y),(G, G)\}\). The probability that exactly one spinner lands on green is \(\frac{4}{9}\).
Sample spaces for compound events 68
A design result is described by a shape, a number, and a pattern. Shape: circle \((C)\) or square \((Q)\) Number: \(1\) or \(2\) Pattern: solid \((O)\) or striped \((T)\) The outcome \(Q2T\) is unavailable. Write the possible sample space. Then list the outcomes with number \(2\).

Hints

- First list the combinations before applying the restriction. - Remove only the specifically unavailable outcome. - Filter the remaining outcomes by the number condition.

Solution

1. Without the restriction, the outcomes are \(C1O,\ C1T,\ C2O,\ C2T,\ Q1O,\ Q1T,\ Q2O,\ Q2T\). 2. Remove the unavailable outcome \(Q2T\). 3. The sample space is \(\{C1O,C1T,C2O,C2T,Q1O,Q1T,Q2O\}\). 4. The outcomes with number \(2\) are \(C2O,\ C2T,\ Q2O\).

Answer

Sample space: \(\{C1O,C1T,C2O,C2T,Q1O,Q1T,Q2O\}\). Number \(2\): \(\{C2O,C2T,Q2O\}\).
Sample spaces for compound events 69
Spinner A and Spinner B are shown. Tereza makes this sample-space table. <table> <tr> <th>Spinner A</th> <th>\(1\)</th> <th>\(2\)</th> <th>\(3\)</th> </tr> <tr> <td>A</td> <td>\((A, 1)\)</td> <td>\((A, 2)\)</td> <td>\((A, 3)\)</td> </tr> <tr> <td>B</td> <td>\((B, 1)\)</td> <td>\((B, 2)\)</td> <td>\((B, 2)\)</td> </tr> </table> a) Identify the table error and give the correct entry. b) Using the corrected table, find the probability that Spinner B shows \(2\).
Figure for problem 554685

Hints

- Check whether each row-column combination appears exactly once. - Use the row and column headings together to inspect the final cell. - After correcting the grid, count the equally likely outcomes in which Spinner B shows \(2\).

Solution

1. The final cell is in row B and column \(3\), so it should be \((B, 3)\), not a second copy of \((B, 2)\). 2. The corrected table has \(6\) distinct equally likely outcomes. 3. Spinner B shows \(2\) in exactly two outcomes: \((A, 2)\) and \((B, 2)\). 4. Therefore, the probability is \(\frac{2}{6}=\frac{1}{3}\).

Answer

a) The last entry should be \((B, 3)\), not \((B, 2)\). b) \(\frac{1}{3}\)
Sample spaces for compound events 70
A fair twelve-sided die is rolled three times. a) How many ordered three-roll results have no repeated number? Use this count to find the theoretical probability that at least one number is repeated. b) In \(1000\) simulated trials of three rolls, at least one repeat occurred in \(241\) trials. Find the relative frequency and the exact absolute difference from the theoretical probability. c) Explain how the simulation results relate to the theoretical probability as the number of trials grows.

Hints

- Count the ordered results of three rolls, then count the ones with three different numbers. - The complement of “at least one repeat” is “all three are different.” - Compare the model probability with the observed frequency using a common denominator. - Many independent repetitions make an experimental estimate more stable, not exact every time.

Solution

1. There are \(12^3=1728\) ordered three-roll results. 2. To have no repeats, there are \(12\) choices for the first roll, \(11\) for the second, and \(10\) for the third, giving \(12\cdot11\cdot10=1320\) results. 3. The probability of no repeats is \(\frac{1320}{1728}=\frac{55}{72}\). Therefore, the probability of at least one repeat is \(1-\frac{55}{72}=\frac{17}{72}\). 4. The experimental probability is \(\frac{241}{1000}\). The absolute difference is \(\frac{241}{1000}-\frac{17}{72}=\frac{11}{2250}\). 5. With many independent trials, the relative frequency tends to stabilize near the theoretical probability, although finite results still vary.

Answer

a) \(1320\) ordered results have no repeated number; \(P(\text{at least one repeat})=\frac{17}{72}\). b) Relative frequency: \(\frac{241}{1000}\); absolute difference: \(\frac{11}{2250}\). c) With more trials, the relative frequency tends to approach the theoretical probability.
Sample spaces for compound events 71
The \(8\)-section spinner shown is spun three times. Find the probability of each event. a) Exactly two spins land on yellow. b) Orange occurs at least once. c) The colors occur in the exact order green, yellow, orange. d) Yellow occurs at most once.
Figure for problem 536022

Hints

- Read the one-spin color probabilities from the spinner. - For “exactly,” account for the possible positions of the specified color. - For “at least once,” consider a complement; for an exact order, multiply in that order.

Solution

1. From the spinner, \(P(\text{green})=\frac{3}{8}\), \(P(\text{yellow})=\frac{1}{2}\), and \(P(\text{orange})=\frac{1}{8}\). 2. Exactly two yellow spins can occur in three positions, so part a is \(3\cdot\left(\frac{1}{2}\right)^2\cdot\frac{1}{2}=\frac{3}{8}\). 3. For part b, use the complement: \(1-\left(\frac{7}{8}\right)^3=\frac{169}{512}\). 4. For the exact order in part c, \(\frac{3}{8}\cdot\frac{1}{2}\cdot\frac{1}{8}=\frac{3}{128}\). 5. At most one yellow means zero or one yellow. Those probabilities are \(\frac{1}{8}\) and \(\frac{3}{8}\), totaling \(\frac{1}{2}\).

Answer

a) \(\frac{3}{8}\) b) \(\frac{169}{512}\) c) \(\frac{3}{128}\) d) \(\frac{1}{2}\)
Sample spaces for compound events 72
The spinner shown has \(4\) equal sections and is spun three times. The ordered color sequence is recorded. Find the probability of each event: a) The colors occur in the order red, blue, yellow. b) All three spins show the same color. c) Exactly two different colors occur. d) Yellow occurs at least once.
Figure for problem 536074

Hints

- Read the four equally likely color outcomes from the spinner. - For part b, count one repeated-color sequence for each color. - For part c, choose two colors and count sequences that actually use both; for part d, consider a complement.

Solution

1. There are \(4^3=64\) equally likely ordered color sequences. 2. The sequence red-blue-yellow is one outcome, so part a is \(\frac{1}{64}\). 3. There are four same-color sequences, so part b is \(\frac{4}{64}=\frac{1}{16}\). 4. There are \(6\) possible pairs of colors. For each pair, \(2^3-2=6\) sequences use both colors, so part c is \(\frac{36}{64}=\frac{9}{16}\). 5. For part d, the complement has no yellow and therefore \(3^3=27\) sequences. Thus, the probability is \(1-\frac{27}{64}=\frac{37}{64}\).

Answer

a) \(\frac{1}{64}\) b) \(\frac{1}{16}\) c) \(\frac{9}{16}\) d) \(\frac{37}{64}\)

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