Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 3: Probability Topics

65 problems · 11 figures

3-1 §3.1 source ↗

In a particular college class, there are male and female students. Some students have long hair and some students have short hair. Write the symbols for the probabilities of the events for parts A through J of this question. Note that you cannot find numerical answers here. You were not given enough information to find any probability values yet; concentrate on understanding the symbols.

• Let F be the event that a student is female.

• Let M be the event that a student is male.

• Let S be the event that a student has short hair.

• Let L be the event that a student has long hair.

a. The probability that a student does not have long hair.

b. The probability that a student is male or has short hair.

c. The probability that a student is female and has long hair.

d. The probability that a student is male, given that the student has long hair.

e. The probability that a student has long hair, given that the student is male.

f. Of all female students, the probability that a student has short hair.

g. Of all students with long hair, the probability that a student is female.

h. The probability that a student is female or has long hair.

i. The probability that a randomly selected student is a male student with short hair.

j. The probability that a student is female.

Answer

a. P(L′) = P(S)

b. P(M OR S)

c. P(F AND L)

d. P(M|L)

e. P(L|M)

f. P(S|F)

g. P(F|L)

h. P(F OR L)

i. P(M AND S)

j. P(F)

3-3 §3.1 source ↗

Use the following information to answer the next four exercises. A box is filled with several party favors. It contains 12 hats, 15 noisemakers, 10 finger traps, and five bags of confetti.
Let H = the event of getting a hat.
Let N = the event of getting a noisemaker.
Let F = the event of getting a finger trap.
Let C = the event of getting a bag of confetti.

Find P(N).

Answer

P(N) = 15 42 = 5 14 = .36

3-5 §3.1 source ↗

Use the following information to answer the next four exercises. A box is filled with several party favors. It contains 12 hats, 15 noisemakers, 10 finger traps, and five bags of confetti.
Let H = the event of getting a hat.
Let N = the event of getting a noisemaker.
Let F = the event of getting a finger trap.
Let C = the event of getting a bag of confetti.

Find P(C).

Answer

P(C) = 5 42 = .12

3-7 §3.1 source ↗


Use the following information to answer the next six exercises. A jar of 150 jelly beans contains 22 red jelly beans, 38 yellow, 20 green, 28 purple, 26 blue, and the rest are orange.
Let B = the event of getting a blue jelly bean
Let G = the event of getting a green jelly bean.
Let O = the event of getting an orange jelly bean.
Let P = the event of getting a purple jelly bean.
Let R = the event of getting a red jelly bean.
Let Y = the event of getting a yellow jelly bean.

Find P(G).

Answer

P(G) = 20 150 = 2 15 = .13

3-9 §3.1 source ↗


Use the following information to answer the next six exercises. A jar of 150 jelly beans contains 22 red jelly beans, 38 yellow, 20 green, 28 purple, 26 blue, and the rest are orange.
Let B = the event of getting a blue jelly bean
Let G = the event of getting a green jelly bean.
Let O = the event of getting an orange jelly bean.
Let P = the event of getting a purple jelly bean.
Let R = the event of getting a red jelly bean.
Let Y = the event of getting a yellow jelly bean.

Find P(R).

Answer

P(R) = 22 150 = 11 75 = .15

3-11 §3.1 source ↗


Use the following information to answer the next six exercises. A jar of 150 jelly beans contains 22 red jelly beans, 38 yellow, 20 green, 28 purple, 26 blue, and the rest are orange.
Let B = the event of getting a blue jelly bean
Let G = the event of getting a green jelly bean.
Let O = the event of getting an orange jelly bean.
Let P = the event of getting a purple jelly bean.
Let R = the event of getting a red jelly bean.
Let Y = the event of getting a yellow jelly bean.

Find P(O).

Answer

P(O) = 150−22−38−20−28−26 150 = 16 150 = 8 75 = .11

3-13 §3.1 source ↗


Use the following information to answer the next six exercises. There are 23 countries in North America, 12 countries in South America, 47 countries in Europe, 44 countries in Asia, 54 countries in Africa, and 14 countries in Oceania (Pacific Ocean region).
Let A = the event that a country is in Asia.
Let E = the event that a country is in Europe.
Let F = the event that a country is in Africa.
Let N = the event that a country is in North America.
Let O = the event that a country is in Oceania.
Let S = the event that a country is in South America.

Find P(E).

Answer

P(E) = 47 194 = .24

3-15 §3.1 source ↗


Use the following information to answer the next six exercises. There are 23 countries in North America, 12 countries in South America, 47 countries in Europe, 44 countries in Asia, 54 countries in Africa, and 14 countries in Oceania (Pacific Ocean region).
Let A = the event that a country is in Asia.
Let E = the event that a country is in Europe.
Let F = the event that a country is in Africa.
Let N = the event that a country is in North America.
Let O = the event that a country is in Oceania.
Let S = the event that a country is in South America.

Find P(N).

Answer

P(N) = 23 194 = .12

3-17 §3.1 source ↗


Use the following information to answer the next six exercises. There are 23 countries in North America, 12 countries in South America, 47 countries in Europe, 44 countries in Asia, 54 countries in Africa, and 14 countries in Oceania (Pacific Ocean region).
Let A = the event that a country is in Asia.
Let E = the event that a country is in Europe.
Let F = the event that a country is in Africa.
Let N = the event that a country is in North America.
Let O = the event that a country is in Oceania.
Let S = the event that a country is in South America.

Find P(S).

Answer

P(S) = 12 194 = 6 97 = .06

3-19 §3.1 source ↗


Use the following information to answer the next six exercises. There are 23 countries in North America, 12 countries in South America, 47 countries in Europe, 44 countries in Asia, 54 countries in Africa, and 14 countries in Oceania (Pacific Ocean region).
Let A = the event that a country is in Asia.
Let E = the event that a country is in Europe.
Let F = the event that a country is in Africa.
Let N = the event that a country is in North America.
Let O = the event that a country is in Oceania.
Let S = the event that a country is in South America.

What is the probability of drawing a club in a standard deck of 52 cards?

Answer

13 52 = 1 4 = .25

3-21 §3.1 source ↗


Use the following information to answer the next six exercises. There are 23 countries in North America, 12 countries in South America, 47 countries in Europe, 44 countries in Asia, 54 countries in Africa, and 14 countries in Oceania (Pacific Ocean region).
Let A = the event that a country is in Asia.
Let E = the event that a country is in Europe.
Let F = the event that a country is in Africa.
Let N = the event that a country is in North America.
Let O = the event that a country is in Oceania.
Let S = the event that a country is in South America.

What is the probability of rolling a prime number of dots with a fair, six-sided die numbered one through six?

Answer

3 6 = 1 2 = .5

3-23 §3.1 source ↗


Use the following information to answer the next two exercises. You see a game at a local fair. You have to throw a dart at a color wheel. Each section on the color wheel is equal in area.


Let B = the event of landing on blue.
Let R = the event of landing on red.
Let G = the event of landing on green.
Let Y = the event of landing on yellow.

If you land on red, you don’t get a prize. What is P(R)?

Figure 3.19 in the book ↗

Answer

P(R)= 4 8 =.5

3-25 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

Write the symbols for the probability that a player is an outfielder or is a great hitter.

Answer

P(O OR H)

3-27 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

Write the symbols for the probability that a player is a great hitter, given that the player is an infielder.

Answer

P(H|I)

3-29 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

Write the symbols for the probability that of all the outfielders, a player is not a great hitter.

Answer

P(N|O)

3-31 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

Write the symbols for the probability that a player is an infielder or is not a great hitter.

Answer

P(I OR N)

3-33 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

Write the symbols for the probability that a player is an infielder.

Answer

P(I)

3-35 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

What is conditional probability?

Answer

The likelihood that an event will occur given that another event has already occurred.

3-37 §3.1 source ↗


Use the following information to answer the next 10 exercises. On a baseball team, there are infielders and outfielders. Some players are great hitters, and some players are not great hitters.
Let I = the event that a player in an infielder.
Let O = the event that a player is an outfielder.
Let H = the event that a player is a great hitter.
Let N = the event that a player is not a great hitter.

What is the sum of the probabilities of an event and its complement?

Answer

1

3-39 §3.1 source ↗


Use the following information to answer the next two exercises. You are rolling a fair, six-sided number cube. Let E = the event that it lands on an even number. Let M = the event that it lands on a multiple of three.

What does P(E OR M) mean in words?

Answer

the probability of landing on an even number or a multiple of three

3-41 §3.2 source ↗

J and K are independent events. P(J|K) = .3. Find P(J).

Answer

P(J) = .3

3-43 §3.2 source ↗

Q and R are independent events. P(Q) = .4 and P(Q AND R) = .1. Find P(R).

Answer

P(Q AND R) = P(Q)P(R)

.1 = (.4)P(R)

P(R) = .25

3-45 §3.3 source ↗

Use the following information to answer the next 10 exercises. Forty-eight percent of all voters of a certain state prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Among Latino registered voters in this state, 55 percent prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Of all citizens in this state, 37.6 percent are Latino.

In this problem, let

Suppose that one citizen is randomly selected.

Find P(L).

Answer

0.376

3-47 §3.3 source ↗

Use the following information to answer the next 10 exercises. Forty-eight percent of all voters of a certain state prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Among Latino registered voters in this state, 55 percent prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Of all citizens in this state, 37.6 percent are Latino.

In this problem, let

Suppose that one citizen is randomly selected.

In words, what is C|L?

Answer

C|L means, given the person chosen is a Latino Californian, the person is a registered voter who prefers life in prison without parole for a person convicted of first degree murder.

3-49 §3.3 source ↗

Use the following information to answer the next 10 exercises. Forty-eight percent of all voters of a certain state prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Among Latino registered voters in this state, 55 percent prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Of all citizens in this state, 37.6 percent are Latino.

In this problem, let

Suppose that one citizen is randomly selected.

In words, what is L AND C?

Answer

L AND C is the event that the person chosen is a voter of the ethnicity in question who prefers life without parole over the death penalty for a person convicted of first degree murder.

3-51 §3.3 source ↗

Use the following information to answer the next 10 exercises. Forty-eight percent of all voters of a certain state prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Among Latino registered voters in this state, 55 percent prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Of all citizens in this state, 37.6 percent are Latino.

In this problem, let

Suppose that one citizen is randomly selected.

Find P(L OR C).

Answer

.6492

3-53 §3.3 source ↗

Use the following information to answer the next 10 exercises. Forty-eight percent of all voters of a certain state prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Among Latino registered voters in this state, 55 percent prefer life in prison without parole over the death penalty for a person convicted of first-degree murder. Of all citizens in this state, 37.6 percent are Latino.

In this problem, let

Suppose that one citizen is randomly selected.

Are L and C mutually exclusive events? Show why or why not.

Answer

No, because P(L AND C) does not equal 0.

3-55 §3.4 source ↗

Use the following information to answer the next four exercises. Table 3.16 shows a random sample of musicians and how they learned to play their instruments.

Find P(musician is a male AND had private instruction).

Table 3.16 in the book ↗
Gender Self-Taught Studied in School Private Instruction Total
Female 12 38 22 72
Male 19 24 15 58
Total 31 62 37 130

Answer

P(musician is a male AND had private instruction) = 15 130 = 3 26 = .12

3-57 §3.4 source ↗

Use the following information to answer the next four exercises. Table 3.16 shows a random sample of musicians and how they learned to play their instruments.

Are the events being a female musician and learning music in school mutually exclusive events?

Table 3.16 in the book ↗
Gender Self-Taught Studied in School Private Instruction Total
Female 12 38 22 72
Male 19 24 15 58
Total 31 62 37 130

Answer

P(being a female musician AND learning music in school) = 38 130 = 19 65 = .29

P(being a female musician)P(learning music in school) = ( 72 130 )( 62 130 ) = 4,464 16,900 = 1,116 4,225 = .26

No, they are not independent because P(being a female musician AND learning music in school) is not equal to P(being a female musician)P(learning music in school).

3-58 §3.5 source ↗

The probability that a man develops some form of cancer in his lifetime is 0.4567. The probability that a man has at least one false-positive test result, meaning the test comes back for cancer when the man does not have it, is .51. Let C = a man develops cancer in his lifetime; P = a man has at least one false-positive test. Construct a tree diagram of the situation.

Answer

Figure 3.23 in the book ↗

3-60 §3.BIT source ↗

Use the following information to answer the next seven exercises. An article in the New England Journal of Medicine, reported about a study of people who use a product in California and Hawaii. In one part of the report, the self-reported ethnicity and using the product levels per day were given. Of the people using the product at most 10 times a day, there were 9,886 African Americans, 2,745 Native Hawaiians, 12,831 Latinos, 8,378 Japanese Americans, and 7,650 whites. Of the people using the product 11 to 20 times per day, there were 6,514 African Americans, 3,062 Native Hawaiians, 4,932 Latinos, 10,680 Japanese Americans, and 9,877 whites. Of the people using the product 21 to 30 times per day, there were 1,671 African Americans, 1,419 Native Hawaiians, 1,406 Latinos, 4,715 Japanese Americans, and 6,062 Whites. Of the people using the product at least 31 times per day, there were 759 African Americans, 788 Native Hawaiians, 800 Latinos, 2,305 Japanese Americans, and 3,970 whites.

Suppose that one person from the study is randomly selected. Find the probability that the person used the product 11 to 20 times per day.

Answer

35,065100,450

3-62 §3.BIT source ↗

Use the following information to answer the next seven exercises. An article in the New England Journal of Medicine, reported about a study of people who use a product in California and Hawaii. In one part of the report, the self-reported ethnicity and using the product levels per day were given. Of the people using the product at most 10 times a day, there were 9,886 African Americans, 2,745 Native Hawaiians, 12,831 Latinos, 8,378 Japanese Americans, and 7,650 whites. Of the people using the product 11 to 20 times per day, there were 6,514 African Americans, 3,062 Native Hawaiians, 4,932 Latinos, 10,680 Japanese Americans, and 9,877 whites. Of the people using the product 21 to 30 times per day, there were 1,671 African Americans, 1,419 Native Hawaiians, 1,406 Latinos, 4,715 Japanese Americans, and 6,062 Whites. Of the people using the product at least 31 times per day, there were 759 African Americans, 788 Native Hawaiians, 800 Latinos, 2,305 Japanese Americans, and 3,970 whites.

In words, explain what it means to pick one person from the study who is Japanese American AND uses the product 21 to 30 times per day. Also, find the probability.

Answer

To pick one person from the study who is Japanese American AND uses the product 21 to 30 times a day means that the person has to meet both criteria: both Japanese American and uses the product 21 to 30 times a day. The sample space should include everyone in the study. The probability is 4,715100,450.

3-64 §3.BIT source ↗

Use the following information to answer the next seven exercises. An article in the New England Journal of Medicine, reported about a study of people who use a product in California and Hawaii. In one part of the report, the self-reported ethnicity and using the product levels per day were given. Of the people using the product at most 10 times a day, there were 9,886 African Americans, 2,745 Native Hawaiians, 12,831 Latinos, 8,378 Japanese Americans, and 7,650 whites. Of the people using the product 11 to 20 times per day, there were 6,514 African Americans, 3,062 Native Hawaiians, 4,932 Latinos, 10,680 Japanese Americans, and 9,877 whites. Of the people using the product 21 to 30 times per day, there were 1,671 African Americans, 1,419 Native Hawaiians, 1,406 Latinos, 4,715 Japanese Americans, and 6,062 Whites. Of the people using the product at least 31 times per day, there were 759 African Americans, 788 Native Hawaiians, 800 Latinos, 2,305 Japanese Americans, and 3,970 whites.

In words, explain what it means to pick one person from the study who is Japanese American GIVEN that the person uses the product 21 to 30 times per day. Also, find the probability.

Answer

To pick one person from the study who is Japanese American given that person uses the product 21 to 30 times a day, means that the person must fulfill both criteria and the sample space is reduced to those who uses the product 21 to 30 times a day. The probability is 471515,273.

3-67 §3.1 source ↗

Explain what is wrong with the following statements. Use complete sentences.

a. If there is a 60 percent chance of rain on Saturday and a 70 percent chance of rain on Sunday, then there is a 130 percent chance of rain over the weekend.

b. The probability that a baseball player hits a home run is greater than the probability that he gets a successful hit.

Answer

a. You can't calculate the joint probability knowing the probability of both events occurring, which is not in the information given; the probabilities should be multiplied, not added; and probability is never greater than 100 percent

b. A home run by definition is a successful hit, so he has to have at least as many successful hits as home runs.

3-69 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

Find the probability that a Health Index Score is 81.0.

Figure 3.21 in the book ↗

Answer

0

3-71 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

Find the probability that a Health Index Score is between 80.5 and 82.

Figure 3.21 in the book ↗

Answer

.3571

3-73 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

What is the probability that a Health Index Score is 80.7 or 82.7?

Figure 3.21 in the book ↗

Answer

.2142

3-75 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

What occupation has the highest Health Index Score?

Figure 3.21 in the book ↗

Answer

Physician (83.7)

3-77 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

What is the range of the data?

Figure 3.21 in the book ↗

Answer

83.7 − 79.6 = 4.1

3-79 §3.2 source ↗

Use the following information to answer the next 12 exercises. The graph shown is based on more than 170,000 interviews that took place from January through December 2012. The sample consists of employed Americans 18 years of age or older. The Health Index Scores are the sample space. We randomly sample one type of Health Index Score, the emotional well-being score.

If all occupations are equally likely for a certain individual, what is the probability that he or she will have an occupation with lower than average Health Index Score?

Figure 3.21 in the book ↗

Answer

P(Occupation < 81.3) = .5

3-81 §3.3 source ↗

After a mayor of a major Canadian city announced his plans to cut budget costs in late 2011, researchers polled 1,046 people to measure the mayor’s popularity. Everyone polled expressed either approval or disapproval. These are the results their poll produced:

• In early 2011, 60 percent of the population approved of the mayor's actions in office.

• In mid-2011, 57 percent of the population approved of his actions.

• In late 2011, the percentage of popular approval was measured at 42 percent.

a. What is the sample size for this study?

b. What proportion in the poll disapproved of the mayor, according to the results from late 2011?

c. How many people polled responded that they approved of the mayor in late 2011?

d. What is the probability that a person supported the mayor, based on the data collected in mid-2011?

e. What is the probability that a person supported the mayor, based on the data collected in early 2011?

Answer

a. The Forum Research surveyed 1,046 Torontonians.

b. 58 percent

c. 42 percent of 1,046 = 439 (rounding to the nearest integer)

d. .57

e. .60.

3-82 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

a. List the sample space of the possible items that are on the menu.

b. Find P(you will get a 17-oz. piece of meat).

c. Find P(you will get a pork chop).

d. Find P(you will get a 17-oz. pork chop).

e. Is getting a pork chop the complement of getting a chicken breast? Why?

f. Find two mutually exclusive events.

g. Are the events getting 17 oz. of meat and getting a pork chop independent?

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. yes; P(getting a pork chop) = P(not getting a chicken breast)

b. getting a pork chop and getting a chicken breast

c. no

3-83 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Compute the probabilities.

a. P(you will get a chicken breast)

b. P(you will get a 17-oz. chicken breast)

c. P(you will get a chicken breast or you will not get a 17-oz. pork chop)

d. P(you will not get a chicken breast and you will get an 18-oz. pork chop)

e. P(you will get a piece of meat that is not 21 oz.)

f. P(you will get a piece of chicken that is not 21 oz.)

g. P(you will not get a chicken breast and you will not get a pork chop)

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. 20/40 = 1/2

b. 5/40 = 1/8

c. 39/40

d. 4/40 = 1/10

e. 33/40

f. 15/40 = 3/8

g. 0/40 = 0

3-84 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Compute the probabilities:

a. P(you will not get a pork chop)

b. P(you will get a 20-oz. pork chop)

c. P(you will not get a chicken breast or you will not get an 18-oz. pork chop)

d. P(you will not get a chicken breast and you will not get an 18-oz. pork chop)

e. P(you will get a pork chop that is not 21 oz.)

f. P(you will not get a chicken breast or you will not get a pork chop)

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

Compute the probabilities.

a. 20/40 = 1/2

b. 8/40 = 1/5

c. 40/40 = 1

d. 16/40 = 2/5

e. 18/40 = 9/20

f. 40/40 = 1

3-85 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Suppose that you have eight cards. Five are green and three are yellow. The five green cards are numbered 1, 2, 3, 4, and 5. The three yellow cards are numbered 1, 2, and 3. The cards are well shuffled. You randomly draw one card.

• G = card drawn is green

• E = card drawn is even-numbered

a. List the sample space.

b. P(G) = ________

c. P(G|E) = ________

d. P(G AND E) = ________

e. P(G OR E) = ________

f. Are G and E mutually exclusive? Justify your answer numerically.

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. {G1, G2, G3, G4, G5, Y1, Y2, Y3}

b. 5 8

c. 2 3

d. 2 8

e. 6 8

f. No, because P(G AND E) does not equal 0.

3-87 §3.3 source ↗

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

A special deck of cards has 10 cards. Four are green, three are blue, and three are red. When a card is picked, its color is recorded. An experiment consists of first picking a card and then tossing a coin.

a. List the sample space.

b. Let A be the event that a blue card is picked first, followed by landing a head on the coin toss. Find P(A).

c. Let B be the event that a red or green is picked, followed by landing a head on the coin toss. Are the events A and B mutually exclusive? Explain your answer in one to three complete sentences, including numerical justification.

d. Let C be the event that a red or blue is picked, followed by landing a head on the coin toss. Are the events A and C mutually exclusive? Explain your answer in one to three complete sentences, including numerical justification.

Answer

NOTE

The coin toss is independent of the card picked first.

a. {(G,H) (G,T) (B,H) (B,T) (R,H) (R,T)}

b. P(A) = P(blue)P(head) = ( 3 10 ) ( 1 2 ) = 3 20

c. Yes, A and B are mutually exclusive because they cannot happen at the same time; you cannot pick a card that is both blue and also (red or green). P(A AND B) = 0.

d. No, A and C are not mutually exclusive because they can occur at the same time. In fact, C includes all of the outcomes of A; if the card chosen is blue it is also (red or blue). P(A AND C) = P(A) = 3 20 .

3-89 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

An experiment consists of tossing a nickel, a dime, and a quarter. Of interest is the side the coin lands on.

a. List the sample space.

b. Let A be the event that there are at least two tails. Find P(A).

c. Let B be the event that the first and second tosses land on heads. Are the events A and B mutually exclusive? Explain your answer in one to three complete sentences, including justification.

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. S = {(HHH), (HHT), (HTH), (HTT), (THH), (THT), (TTH), (TTT)}

b. 4 8

c. Yes, because if A has occurred, it is impossible to obtain two tails. In other words, P(A AND B) = 0.

3-91 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Y and Z are independent events.

a. Rewrite the basic Addition Rule P(Y OR Z) = P(Y) + P(Z) - P(Y AND Z) using the information that Y and Z are independent events.

b. Use the rewritten rule to find P(Z) if P(Y OR Z) = .71 and P(Y) = .42.

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. If Y and Z are independent, then P(Y AND Z) = P(Y)P(Z), so P(Y OR Z) = P(Y) + P(Z) – P(Y)P(Z).

b. .5

3-93 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Approximately 281,000,000 people over age five live in the United States. Of these people, 55,000,000 speak a language other than English at home. Of those who speak another language at home, 62.3 percent speak Spanish.

Let E = speaks English at home; E′ = speaks another language at home; and S = speaks Spanish.

Finish each probability statement by matching the correct answer.

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20
Table 3.19 in the book ↗
Probability Statements Answers
a. P(E′) = i. .8043
b. P(E) = ii. .623
c. P(S and E′) = iii. .1957
d. P(S|E′) = iv. .1219

Answer

iii i iv ii

3-95 §3.3 source ↗

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

Three professors at George Washington University did an experiment to determine if economists are more likely to return found money than other people. They dropped 64 stamped, addressed envelopes with $10 cash in different classrooms on the George Washington campus. Forty-four percent were returned overall. From the economics classes 56 percent of the envelopes were returned. From the business, psychology, and history classes 31 percent were returned.

Let R = money returned; E = economics classes; and O = other classes.

a. Write a probability statement for the overall percentage of money returned.

b. Write a probability statement for the percentage of money returned out of the economics classes.

c. Write a probability statement for the percentage of money returned out of the other classes.

d. Is money being returned independent of the class? Justify your answer numerically and explain it.

e. Based upon this study, do you think that economists are more selfish than other people? Explain why or why not. Include numbers to justify your answer.

Answer

a. P(R) = .44

b. P(R|E) = .56

c. P(R|O) = .31

d. No, whether the money is returned is not independent of which class the money was placed in. There are several ways to justify this mathematically, but one is that the money placed in economics classes is not returned at the same overall rate; P(R|E) ≠ P(R).

e. No, this study definitely does not support that notion; in fact, it suggests the opposite. The money placed in the economics classrooms was returned at a higher rate than the money place in all classes collectively; P(R|E) > P(R).

3-97 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

United Blood Services is a blood bank that serves more than 500 hospitals in 18 states. According to their website, a person with type O blood and a negative Rh factor (Rh–) can donate blood to any person with any bloodtype. Their data show that 43 percent of people have type O blood and 15 percent of people have Rh– factor; 52 percent of people have type O or Rh– factor.

a. Find the probability that a person has both type O blood and the Rh– factor.

b. Find the probability that a person does not have both type O blood and the Rh– factor.

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a.

P(type O OR Rh–) = P(type O) + P(Rh–) – P(type O AND Rh–)

0.52 = 0.43 + 0.15 – P(type O AND Rh–); solve to find P(type O AND Rh–) = .06

6 percent of people have type O, Rh– blood

b.

P(NOT(type O AND Rh–)) = 1 – P(type O AND Rh–) = 1 – .06 = .94

94 percent of people do not have type O, Rh– blood

3-99 §3.3 source ↗

Use the following information to answer the next three exercises. A local restaurant sells pork chops and chicken breasts. The given values below are the weights (in ounces) of pork chops and chicken breasts listed on the menu. Your server will randomly select one piece of meat (pork chop or chicken breast) that you will be served.

In a box of assorted cookies, 36 percent contain chocolate and 12 percent contain nuts. Of those, 8 percent contain both chocolate and nuts. Sean is allergic to both chocolate and nuts.

a. Find the probability that a cookie contains chocolate or nuts (he can't eat it).

b. Find the probability that a cookie does not contain chocolate or nuts (he can eat it).

Table 3.18 in the book ↗
Pork Chops 17 20 21 18 20 20 20 18 19 19
20 19 21 20 18 20 20 19 18 19
Chicken Breasts 17 19 17 21 17 21 18 21 19 21
20 17 20 18 19 20 20 17 21 20

Answer

a. Let C = be the event that the cookie contains chocolate. Let N = the event that the cookie contains nuts.

b. P(C OR N) = P(C) + P(N) – P(C AND N) = .36 + .12 – .08 = .40

c. P(NEITHER chocolate NOR nuts) = 1 – P(C OR N) = 1 – .40 = .60

3-101 §3.4 source ↗

Use the information in the Table 3.21 to answer the next eight exercises. The table shows the political party affiliation of each of 67 members of the U.S. Senate in June 2012, and when they would next be up for reelection.

What is the probability that a randomly selected senator had an Other affiliation?

Table 3.21 in the book ↗
Up for Reelection: Democratic Party Republican Party Other Total
November 2014 20 13 0
November 2016 10 24 0
Total

Answer

0

3-103 §3.4 source ↗

Use the information in the Table 3.21 to answer the next eight exercises. The table shows the political party affiliation of each of 67 members of the U.S. Senate in June 2012, and when they would next be up for reelection.

What is the probability that a randomly selected senator was a Democrat and was up for reelection in November 2016?

Table 3.21 in the book ↗
Up for Reelection: Democratic Party Republican Party Other Total
November 2014 20 13 0
November 2016 10 24 0
Total

Answer

10 67

3-105 §3.4 source ↗

Use the information in the Table 3.21 to answer the next eight exercises. The table shows the political party affiliation of each of 67 members of the U.S. Senate in June 2012, and when they would next be up for reelection.

Suppose that a member of the U.S. Senate is randomly selected. Given that the randomly selected senator was up for reelection in November 2016, what is the probability that this senator was a Democrat?

Table 3.21 in the book ↗
Up for Reelection: Democratic Party Republican Party Other Total
November 2014 20 13 0
November 2016 10 24 0
Total

Answer

10 34

3-107 §3.4 source ↗

Use the information in the Table 3.21 to answer the next eight exercises. The table shows the political party affiliation of each of 67 members of the U.S. Senate in June 2012, and when they would next be up for reelection.

The events Republican and Up for reelection in 2016 are ________.

a. mutually exclusive

b. independent

c. both mutually exclusive and independent

d. neither mutually exclusive nor independent

Table 3.21 in the book ↗
Up for Reelection: Democratic Party Republican Party Other Total
November 2014 20 13 0
November 2016 10 24 0
Total

Answer

d

3-110 §3.4 source ↗

Use the following information to answer the next two exercises. The table of data obtained from www.baseball-almanac.com shows hit information for four well-known baseball players. Suppose that one hit from the table is randomly selected.

Find P(Hit was made by Ty Cobb|The hit was a Home Run).

a. 4,189 12,351

b. 114 1,720

c. 1,720 4,189

d. 114 12,351

Table 3.22 in the book ↗
Name Single Double Triple Home Run Total Hits
Babe Ruth 1,517 506 136 714 2,873
Jackie Robinson 1,054 273 54 137 1,518
Ty Cobb 3,603 174 295 114 4,189
Hank Aaron 2,294 624 98 755 3,771
TOTAL 8,471 1,577 583 1,720 12,351

Answer

b

3-112 §3.4 source ↗

Table 3.22 in the book ↗
Name Single Double Triple Home Run Total Hits
Babe Ruth 1,517 506 136 714 2,873
Jackie Robinson 1,054 273 54 137 1,518
Ty Cobb 3,603 174 295 114 4,189
Hank Aaron 2,294 624 98 755 3,771
TOTAL 8,471 1,577 583 1,720 12,351
Table 3.24 in the book ↗
Shirt # ≤ 210 211–250 251–290 > 290
1–33 21 5 0 0
34–66 6 18 7 4
66–99 6 12 22 5

Use the following information to answer the next two exercises. The table of data obtained from www.baseball-almanac.com shows hit information for four well-known baseball players. Suppose that one hit from the table is randomly selected.

In a previous year, the weights of the members of a California football team and a Texas football team were published in a newspaper. The factual data were compiled into the following table. The weights in the column headings are in pounds.

For the following, suppose that you randomly select one player from the California team or the Texas team.

a. Find the probability that his shirt number is from 1 to 33.

b. Find the probability that he weighs at most 210 pounds.

c. Find the probability that his shirt number is from 1 to 33 AND he weighs at most 210 pounds.

d. Find the probability that his shirt number is from 1 to 33 OR he weighs at most 210 pounds.

e. Find the probability that his shirt number is from 1 to 33 GIVEN that he weighs at most 210 pounds.

Answer

a. 26 106

b. 33 106

c. 21 106

d. ( 26 106 ) + ( 33 106 ) – ( 21 106 ) = ( 38 106 )

e. 21 33

3-114 §3.5 source ↗

Use the following information to answer the next two exercises. This tree diagram shows the tossing of an unfair coin followed by drawing one bead from a cup containing three red (R), four yellow (Y), and five blue (B) beads. For the coin, P(H) = 2 3 and P(T) = 1 3 where H is heads and T is tails.

Find P(blue bead).

a. 15 36

b. 10 36

c. 10 12

d. 6 36

Figure 3.22 in the book ↗

Answer

a

3-117 §3.BIT source ↗

The probability that a male develops some form of cancer in his lifetime is .4567. The probability that a male has at least one false-positive test result, meaning the test comes back for cancer when the man does not have it, is .51. Some of the following questions do not have enough information for you to answer them. Write not enough information for those answers. Let C = a man develops cancer in his lifetime and P = a man has at least one false-positive.

a. P(C) = ______

b. P(P|C) = ______

c. P(P|C') = ______

d. If a test comes up positive, based upon numerical values, can you assume that man has cancer? Justify numerically and explain why or why not.

Answer

a. P(C) = .4567

b. not enough information

c. not enough information

d. no, because over half (0.51) of men have at least one false-positive text

3-119 §3.BIT source ↗

Given events J and K: P(J) = .18; P(K) = .37; P(J OR K) = .45

a. Find P(J AND K).

b. Find the probability of the complement of event (J AND K).

c. Find the probability of the complement of event (J OR K).

Answer

a. P(J OR K) = P(J) + P(K) − P(J AND K); .45 = .18 + .37 – P(J AND K); solve to find P(J AND K) = .10

b. P(NOT (J AND K)) = 1 – P(J AND K) = 1 – 010 = .90

c. P(NOT (J OR K)) = 1 – P(J OR K) = 1 – .45 = .55

3-120 §3.BIT source ↗

Use the following information to answer the next two exercises. Suppose that you have eight cards. Five are green and three are yellow. The cards are well shuffled.

Suppose that you randomly draw two cards, one at a time, with replacement.
Let G1 = first card is green
Let G2 = second card is green

a. Draw a tree diagram of the situation.

b. Find P(G1 AND G2).

c. Find P(at least one green).

d. Find P(G2|G1).

e. Are G2 and G1 independent events? Explain why or why not.

Answer

a.

b. P(GG) = ( 5 8 )( 5 8 ) = 25 64

c. P(at least one green) = P(GG) + P(GY) + P(YG) = 25 64 + 15 64 + 15 64 = 55 64

d. P(G|G) = 5 8

e. Yes, they are independent because the first card is placed back in the bag before the second card is drawn. The composition of cards in the bag remains the same from draw one to draw two.

Figure 3.24 in the book ↗

3-122 §3.BIT source ↗

Use the following information to answer the next two exercises. The percent of licensed U.S. drivers (from a recent year) who are female is 48.60. Of the females, 5.03 percent are age 19 and under; 81.36 percent are age 20–64; 13.61 percent are age 65 or over. Of the licensed U.S. male drivers, 5.04 percent are age 19 and under; 81.43 percent are age 20–64; 13.53 percent are age 65 or over.

Complete the following:

a. Construct a table or a tree diagram of the situation.

b. Find P(driver is female).

c. Find P(driver is age 65 or over|driver is female).

d. Find P(driver is age 65 or over AND female).

e. In words, explain the difference between the probabilities in Part c and Part d.

f. Find P(driver is age 65 or over).

g. Are being age 65 or over and being female mutually exclusive events? How do you know?

Answer

a.

<2020–64>64Totals
Female .0244 .3954 .0661 .486
Male .0259 .4186 .0695 .514
Totals .0503 .8140 .1356 1
Table 3.27

b. P(F) = .486

c. P(>64|F) = .1361

d. P(>64 and F) = P(F) P(>64|F) = (.486)(.1361) = .0661

e. P(>64|F) is the percentage of female drivers who are 65 or older and P(>64 and F) is the percentage of drivers who are female and 65 or older.

f. P(>64) = P(>64 and F) + P(>64 and M) = .1356

g. No, being female and 65 or older are not mutually exclusive because they can occur at the same time P(>64 and F) = .0661.

Table 3.27 in the book ↗
<2020–64>64Totals
Female .0244 .3954 .0661 .486
Male .0259 .4186 .0695 .514
Totals .0503 .8140 .1356 1

3-124 §3.BIT source ↗

Use the following information to answer the next two exercises. The percent of licensed U.S. drivers (from a recent year) who are female is 48.60. Of the females, 5.03 percent are age 19 and under; 81.36 percent are age 20–64; 13.61 percent are age 65 or over. Of the licensed U.S. male drivers, 5.04 percent are age 19 and under; 81.43 percent are age 20–64; 13.53 percent are age 65 or over.

Approximately 86.5 percent of Americans commute to work by car, truck, or van. Out of that group, 84.6 percent drive alone and 15.4 percent drive in a carpool. Approximately 3.9 percent walk to work and approximately 5.3 percent take public transportation.

a. Construct a table or a tree diagram of the situation. Include a branch for all other modes of transportation to work.

b. Assuming that the walkers walk alone, what percent of all commuters travel alone to work?

c. Suppose that 1,000 workers are randomly selected. How many would you expect to travel alone to work?

d. Suppose that 1,000 workers are randomly selected. How many would you expect to drive in a carpool?

Answer

a.

Car, Truck or Van Walk Public Transportation Other Totals
Alone .7318
Not Alone .1332
Totals .8650 .0390 .0530 .0430 1
Table 3.28

b. If we assume that all walkers are alone and that none from the other two groups travel alone (which is a big assumption) we have: P(Alone) = .7318 + .0390 = .7708.

c. Make the same assumptions as in (b) we have: (.7708)(1,000) = 771

d. (.1332)(1,000) = 133

Table 3.28 in the book ↗
Car, Truck or Van Walk Public Transportation Other Totals
Alone .7318
Not Alone .1332
Totals .8650 .0390 .0530 .0430 1

3-126 §3.BIT source ↗

Table 3.26 in the book ↗
Method A Method B Method C Other Totals
Female 0 70 136 49 ____
Male 2,146 463 60 135 ____
Totals ____ ____ ____ ____ ____

Use the following information to answer the next two exercises. The percent of licensed U.S. drivers (from a recent year) who are female is 48.60. Of the females, 5.03 percent are age 19 and under; 81.36 percent are age 20–64; 13.61 percent are age 65 or over. Of the licensed U.S. male drivers, 5.04 percent are age 19 and under; 81.43 percent are age 20–64; 13.53 percent are age 65 or over.

Use the following information to answer the next two exercises. The following are real data from Santa Clara County, California. As of a certain time, there had been a total of 3,059 documented cases of a disease in the county. They were grouped into the following categories, with risk factors of becoming ill with the disease labeled as Methods A, B, and C and Other:

Suppose a person with a disease in Santa Clara County is randomly selected.

a. Find P(Person is female).

b. Find P(Person has a risk factor of method C).

c. Find P(Person is female OR has a risk factor of method B).

d. Find P(Person is female AND has a risk factor of method A).

e. Find P(Person is male AND has a risk factor of method B).

f. Find P(Person is female GIVEN person got the disease from method C).

g. Construct a Venn diagram. Make one group females and the other group method C.

Answer

The completed contingency table is as follows:

Method A Method B Method C Other Totals
Female 0 70 136 49 255
Male 2,146 463 60 135 2,804
Totals 2,146 533 196 184 3,059
Table 3.29

a. 255 3059

b. 196 3059

c. 718 3059

d. 0

e. 463 3059

f. 136 196

g.

Table 3.29 in the book ↗
Method A Method B Method C Other Totals
Female 0 70 136 49 255
Male 2,146 463 60 135 2,804
Totals 2,146 533 196 184 3,059
Figure 3.25 in the book ↗

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Problems and answers are adapted from Statistics by Barbara Illowsky and Susan Dean, attributed to the Texas Education Agency (TEA) and published by OpenStax, and are used under the CC BY 4.0 licence. Access for free at https://openstax.org/books/statistics/pages/1-introduction. The original material is available at https://www.texasgateway.org/book/tea-statistics. Changes were made to the original material, including updates to art, structure, and other content updates. Art is credited in its own caption wherever the book credits it. This adaptation is neither affiliated with nor endorsed by OpenStax, Rice University or the Texas Education Agency (TEA).