# 10 Probability Questions

1.

The probability of an event will always be a value greater than zero, but less than or equal to one.

A) True

B) False

2.

If events A and B are mutually exclusive, then P(A) + P(B) = 0.

A) True

B) False

3.

Two events A and B are independent only if the P(A | B) is the same as the P(A).

A) True

B) False

4.

The empirical view of probability is based on relative frequencies of experimental outcomes.

A) True

B) False

5.

A contingency table is a cross-tabulation of frequencies for two variables with categorical outcomes, and can be used to calculate probabilities.

A) True

B) False

6.

Independent events A and B would be consistent with which of the following statements:

A) P (A) = .5, P (B) = .4, P (A ∩ B) = .3

B) P (A) = .4, P (B) = .3, P (A ∩ B) = .5

C) P (A) = .3, P (B) = .5, P (A ∩ B) = .4

D) P (A) = .4, P (B) = .5, P (A ∩ B) = .2

7.

Which of the following statements is true?

A) If A and B are independent events, the P(B) = P(A) P(B).

B) The sum of two mutually exclusive events is one.

C) The probability of A and its complement (A′) will always sum to one.

D) If event (A) occurs, then its complement (A′) will also occur.

8.

Two events are complementary when

A) the sum of their probabilities is one.

B) the joint probability of the two events is one.

C) they are mutually exclusive.

D) None of the above.

9.

If each of two independent file servers has a reliability of 93% and either alone can run the web site, then the overall web site availability is

A) 0.8649

B) 0.9300

C) 0.9522

D) 0.9951

10.

The manager of a Drug Store knows that 50% of the customers entering the store buy prescription drugs, 65% buy over-the-counter drugs, and 18% buy both types of drugs. What is the probability that a randomly selected customer will buy at least one of these two types of drugs?

A) .5

B) .85

C) .97

D) 1.0