PSYCH 311 1 of 4 WSU

A.) Probability

1. The proportion or fraction of times an outcome is likely to occur is referred to as A) probability B) a random event C) sample space D) luck

D.) .03

7. Suppose that the probability that any child of alcoholic parents becomes alcoholic is p = .16. Assuming independent outcomes, the probability that two children of alcoholic parents will be alcoholic equals A) .16 B) .32 C) .25 D) .03

B.) False

13. The probability of an outcome is particularly useful for predicting the likelihood of fixed events. A) True B) False

A.) True

14. Probability ranges between 0 and 1 and is never negative. A) True B) False

B.) 1/3

2. A news poll showed that voters had no preference for either of three candidates. In this example, the probability of a vote for, say, Candidate A equals A) 1/2 B) 1/3 C) 2/3 D) 1.00

B.) Probability Distribution

8. The distribution of probabilities for each outcome of a random variable that sums to 1.00 is called a A) random variable B) probability distribution C) conditional probability D) sample space

D.) .50

9. A professor records the grades for his class of students. He finds that the probability that a student earns an A is p = .14; earns a B is p = .36; earns a C is p = .32; earns a D is p = .10; and earns an F is p = .08. What is the probability that a student earns a B or better in this class? A) .36 B) .14 C) .86 D) .50

D.) The time it takes to complete a driving test.

10. Each of the following is an example of a binomial distribution, except A) the number of heads in ten flips of a fair coin B) the number of males and females in a sample C) the number of votes for or against a candidate D) the time it takes to complete a driving test

C.) Both A and B

11. The mean of a probability distribution is called the A) expected value of the mean B) mathematical expectation C) both A and B D) none of the above

A.) True

12. The sample space is equal to the total number of random outcomes possible for a random variable. A) True B) False

A.) True

15. The probability that a participant is married is p(M) = .60. The probability that a participant is married and "in love" is p(ML) = .46. Thus, the probability that a participant is in love, given that the participant is married is p = .77. A) True B) False

A.) True

16. Probability distributions display the probability of each possible outcome for a given random variable. A) True B) False

A.) True

17. The expected value of a random variable is the mean of a probability distribution. A) True B) False

A.) True

18. While the expected value of the mean estimates the average outcome, the standard deviation of a probability distribution estimates the distance that all other outcomes deviate from the mean. A) True B) False

B.) False

19. A binomial probability distribution is constructed for random variables that have at least two possible outcomes. A) True B) False

D.) All of the above

20. A theoretical distribution that evenly distributes data around the mean, median, and mode is called the A) normal distribution B) bell-shaped distribution C) Gaussian distribution D) all of the above

C.) Approximate

21. Most behavior is believed to ________ a normal distribution. A) be exactly equal to B) not resemble at all C) approximate

D.) -1.28

22. What is the z score for scores in the bottom 10%? A) 1.28 B) 2.32 C) -2.32 D) -1.28

D.) all of the above

23. In a normal distribution, 50% of all data: A) fall above the mean B) fall below the median C) fall above and below the mode D) all of the above

C.) Transform a raw score (x) into a z score

24. Which of the following is not a step to locate a score in a normal distribution? A) Locate a z score associated with a given proportion in the unit normal table. B) Transform the z score into a raw score (x). C) Transform a raw score (x) into a z score.

B.) False

25. In a normal distribution a score of 8 will always be more probable than a score of 0. A) True B) False

A.) 1/6

3. A gambler rolls a 3 with one roll of a single fair die. Given that the die was six-sided, what was the probability of rolling a 3 with one roll? A) 1/6 B) 3/6 C) 1/9 D) 3/9

B.) 2/6

4. The following are six random outcomes for a sample space: -1, -3, -3, -2, -5, and -6. What is the probability of selecting a -3 in this example? A) 1/6 B) 2/6 C) -2/6 D) -3/6

A.) Additive Rule

5. Which rule states that when two outcomes are mutually exclusive, the probability that either one of these outcomes will occur is the sum of their individual probabilities? A) additive rule B) multiplicative rule C) both A and B D) none of the above

A.) .33

6. The probability that someone in the human population has blood type AB is about p = .08; the probability that someone has blood type O is about p = .25. Knowing that each individual can have one and only one blood type, what is the probability that a person has an AB or O blood type? A) .33 B) .02 C) 1.00 D) This state of affairs is not possible.