Chapter 5 MCQ Review

Events D and E are independent, with P( D ) = 0.6 and P( D and E ) = 0.18. Which of the following is true?

• P( E ) = 0.12

• P( E ) = 0.4

• P( D or E ) = 0.28

• P( D or E ) = 0.72

One student from a high school will be selected at random. Let A be the event that the selected student is a student athlete, and let B be the event that the selected student drives to school. If P(A∩B)=0.08 and P(B|A)=0.25, what is the probability that the selected student will be a student athlete?

• 0.02

• 0.17

• 0.32

• 0.33

Each of the faces of a fair six-sided number cube is numbered with one of the numbers 1 through 6, with a different number appearing on each face. Two such number cubes will be tossed, and the sum of the numbers appearing on the faces that land up will be recorded. What is the probability that the sum will be 4, given that the sum is less than or equal to 6 ?

• 2/36

• 3/36

• 3/15

• 2/9

For flights from a particular airport in January, there is a 30 percent chance of a flight being delayed because of icy weather. If a flight is delayed because of icy weather, there is a 10 percent chance the flight will also be delayed because of a mechanical problem. If a flight is not delayed because of icy weather, there is a 5 percent chance that it will be delayed because of a mechanical problem. If one flight is selected at random from the airport in January, what is the probability that the flight selected will have at least one of the two types of delays?

• 0.065

• 0.335

• 0.350

• 0.450

Ali surveyed 200 students at a school and recorded the eye color and the gender of each student. Of the 80 male students who were surveyed, 60 had brown eyes. If eye color and gender are independent, how many female students surveyed would be expected to have brown eyes?

• 5

• 20

• 30

• 90

The SC Electric Company has bid on two electrical wiring jobs. The owner of the company believes that

the probability of being awarded the first job (event A) is 0.75;

the probability of being awarded the second job (event B) is 0.5; and

the probability of being awarded both jobs (event (A and B)) is 0.375.

If the owner’s beliefs are correct, which of the following statements must be true concerning event A and event B ?

• Event A and event B are mutually exclusive and are independent.

• Event A and event B are mutually exclusive and are not independent.

• Event A and event B are not mutually exclusive and are independent

• Event A and event B are not mutually exclusive and are not independent.

At a small company, 40 percent of the employees are classified as junior level, and 32 percent of the employees work in department A. Of those classified as junior level, 55 percent work in department A. One employee will be selected at random.

What is the probability that the selected employee works in department A and is not classified as junior level?

• 0.10

• 0.19

• 0.22

• 0.32

A company is considering purchasing the mineral rights to two different mountains. The probability that it will purchase the mineral rights to the first mountain is 0.55. The probability that it will purchase the mineral rights to the second mountain is 0.4. Assuming the decisions to purchase the mineral rights to each mountain are made independently, what is the probability that it will purchase the mineral rights to exactly one of the two mountains?

• 0.18

• 0.22

• 0.33

• 0.51

Ninety percent of the people who have a particular disease will have a positive result on a given diagnostic test. Ninety percent of the people who do not have the disease will have a negative result on this test. If 5 percent of a certain population has the disease, what percent of that population would test positive for the disease?

• 4.5%

• 5%

• 10%

• 14%

A police officer is using a radar device to check motorists’ speeds. Prior to beginning the speed check, the officer estimates that 40 percent of motorists will be driving more than 5 miles per hour over the speed limit. Assuming that the police officer’s estimate is correct, what is the probability that among 4 randomly selected motorists, the officer will find at least 1 motorist driving more than 5 miles per hour over the speed limit?

• 0.8704

• 0.3456

• 0.1296

• 0.0256