# Chapter 3

Probability

True/False

1. A contingency table is a tabular summary of probabilities concerning two sets of complementary events. Answer: True Difficulty: Medium

2. An event is a collection of sample space outcomes.

Answer: True Difficulty: Easy

3. Two events are independent if the probability of one event is influenced by whether or not the other event occurs. Answer: False Difficulty: Medium

4. Mutually exclusive events have a nonempty intersection. Answer: False Difficulty: Medium (REF)

5. A subjective probability is a probability assessment that is based on experience, intuitive judgment, or expertise. Answer: True Difficulty: Medium

6. The probability of an event is the sum of the probabilities of the sample space outcomes that correspond to the event. Answer: True Difficulty: Medium

7. If events A and B are mutually exclusive, then P( ) is always equal to zero. Answer: True Difficulty: Hard (REF)

8. If events A and B are independent, then P(A|B) is always equal to zero. Answer: False Difficulty: Medium (REF)

9. If events A and B are mutually exclusive, then P(A B) is always equal to zero. Answer: True Difficulty: Easy

10. Events that have no sample space outcomes in common, and, therefore cannot occur simultaneously are referred to as independent events. Answer: False Difficulty: Medium

Multiple Choice

11. Two mutually exclusive events having positive probabilities are ______________ dependent. A) Always

B) Sometimes

C) Never

Answer: A Difficulty: Hard (REF)

12. ___________________ is a measure of the chance that an uncertain event will occur. A) Random experiment

B) Sample Space

C) Probability

D) A complement

E) A population

Answer: C Difficulty: Medium

13. A manager has just received the expense checks for six of her employees. She randomly distributes the checks to the six employees. What is the probability that exactly five of them will receive the correct checks (checks with the correct names). A) 1

B) ½

C) 1/6

D) 0

E) 1/3

Answer: D Difficulty: Hard

14. In which of the following are the two events A and B, always independent? A) A and B are mutually exclusive.

B) The probability of event A is not influenced by the probability of event B. C) The intersection of A and B is zero.

D) P(A/B) = P(A).

E) B and D.

Answer: E Difficulty: Hard (REF)

15. If two events are independent, we can _____ their probabilities to determine the intersection probability. A) Divide

B) Add

C) Multiply

D) Subtract

Answer: C Difficulty: Easy

16. Events that have no sample space outcomes in common, and therefore, cannot occur simultaneously are: A) Independent

B) Mutually Exclusive

C) Intersections

D) Unions

Answer: B Difficulty: Medium

17. If events A and B are independent, then the probability of simultaneous occurrence of event A and event B can be found with: A) P(A)•P(B)

B) P(A)•P( )

C) P(B)•P( )

D) All of the above are correct

Answer: D Difficulty: Hard (REF)

18. The set of all possible experimental outcomes is called a(n): A) Sample space

B) Event

C) Experiment

D) Probability

Answer: A Difficulty: Easy

19. A(n) ____________ is the probability that one event will occur given that we know that another event already has occurred. A) Sample space outcome

B) Subjective Probability

C) Complement of events

D) Long-run relative frequency

E) Conditional probability

Answer: E Difficulty: Medium

20. The _______ of two events X and Y is another event that consists of the sample space outcomes belonging to either event X or event Y or both event X and Y. A) Complement

B) Union

C) Intersection

D) Conditional...

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