PSYCH104 Review - Chapter 5 (Probability and Sampling Distributions)

The distribution of sample means (for a specific sample size) consists of ____. a. all the scores contained in the sample b. the specific sample mean computed for the sample of scores c. all the scores contained in the population d. all the sample means that could be obtained (for the specific sample size)

d. all the sample means that could be obtained (for the specific sample size)

An introductory psychology class has 9 first-year males, 15 first-year females, 8 second-year males, and 12 second-year females. What is the probability of randomly selecting a male from this group? a. 8/20 b. 17/44 c. 9/24 d. 17/20

b. 17/44

A vertical line is drawn through a normal distribution at z = -1.00. The line separates the distribution into two sections and the larger section corresponds to ____ of the whole distribution. a. 75% b. 84.13% c. 99% d. -84.13%

b. 84.13%

A random sample requires that a. the probabilities cannot change during a series of selections b. All of the other 3 choices are correct. c. every individual has an equal chance of being selected d. there must be sampling with replacement

b. All of the other 3 choices are correct.

The probability of getting a z larger than 1 is ___. a. More than the probability of getting a z smaller than -1 (i.e., of z< -1) b. Equal to the probability of getting a z smaller than -1 (i.e., of z< -1) c. Less than the probability of getting a z smaller than -1 (i.e., of z< -1) d. None of the answers provided is correct.

b. Equal to the probability of getting a z smaller than -1 (i.e., of z< -1)

The standard deviation of the distribution of sample means is called ____. a. the central limit mean b. the standard error of M c. the expected value of M d. the sample mean

b. the standard error of M

What proportion of the scores in a normal distribution have z-scores less than z = -1.32? a. 0.0934 b. 0.9066 c. 0.5934 d. 0.4066

a. 0.0934

For any normal distribution, the probability of selecting a score greater than the mean is ____. a. 50% b. 25% c. cannot be determined without additional information d. 34.13%

a. 50%

Which of the following statements is FALSE? a. p(z > 3) is larger than p(z < -3). b. p(z>.9) is smaller than p (z>.5). c. p(z>0) is larger than p(z>1) d. none of the other options is correct

a. p(z > 3) is larger than p(z < -3).

For a normal distribution with μ = 60 with σ = 8, the probability of selecting a score greater than X = 64 is equal to ____. a. the proportion of the distribution with z-scores greater than 0.50 b. the proportion of the distribution with z-scores greater than 2.00 c. the proportion of the distribution with z-scores greater than 4.00 d. the proportion of the distribution with z-scores greater than 1.00

a. the proportion of the distribution with z-scores greater than 0.50

For a normal distribution, the proportion in the tail beyond z = 1.50 is p = 0.0668. Based on this information, what is the proportion in the tail beyond z = -1.50? a. 0.9332 b. -0.9332 c. 0.0668 d. -0.0668

c. 0.0668

A vertical line is drawn through a normal distribution at z = 1.00. The proportion of the distribution that is located between the mean and the line is ____. a. 0.1587 b. 0.8413 c. 0.3413 d. 0.6826

c. 0.3413

For any distribution (normal or not normal), the probability of selecting a score greater than the median is ____. a. 25% b. 34.13% c. 50% d. cannot be determined without additional information

c. 50%

A population has μ = 80 with σ = 8. The distribution of sample means for samples of size n = 4 selected from this population would have an expected value of ____. Select one: a. 20 b. 8 c. 80 d. 40

c. 80

Probability values are always ____. a. less than or equal to 1 b. greater than or equal to 0 c. All of the other 3 choices are correct. d. positive numbers

c. All of the other 3 choices are correct.

A normal distribution has μ = 80 and σ = 10. What is the probability of randomly selecting a score greater than 85 from this distribution? a. p = .50 b. p = .6915 c. p = .3085 d. p = .25

c. p = .3085

A normal distribution has μ = 100 and σ = 20. What is the probability of randomly selecting a score less than 130 from this distribution? a. p = .9032 b. p = .0968 c. p = .9332 d. p = .0668

c. p = .9332

What proportion of a normal distribution is located between z = 1.00 and z = 1.50? a. 0.2255 b. 0.7745 c. 0.5000 d. 0.0919

d. 0.0919

What proportion of the scores in a normal distribution have z-scores less than z = 0.86? a. 0.1949 b. 0.6949 c. 0.3051 d. 0.8051

d. 0.8051

A jar contains 10 red marbles and 20 blue marbles. What is the probability of randomly selecting a red marble? a. 10/20 b. 1/10 c. 1/30 d. 10/30

d. 10/30