1. What position in the distribution corresponds to a z-score of z = 1.00?

a. Below the mean by 1 point

b. Below the mean by a distance equal to 1 standard deviation

c. Above the mean by 1 point

d. Above the mean by a distance equal to 1 standard deviation

2. What z-score corresponds to a score that is below the mean by 2 standard deviations?

a. +2

b. +10

c. +20

d. -2

3. Which of the following z-score values represents the location farthest from the mean?

a. z = +0.50

B. z = +1.00

C. z = -1.00

d. z = –2.00

4. For a population with μ = 100 and σ = 20, what is the X value corresponding to z = –0.75?

a. 85

b. 95

c. 105

d. 115

5. In a population with σ = 8, a score of X = 44 corresponds to a z-score of z = –0.50. What is the population mean?

a. μ = 36

B . μ = 40

C. μ = 48

d. μ = 52

6. For any distribution, what is the z-score corresponding to the mean?

a. 0

b. 1

c. N

d. Cannot be determined from the information given

7. Last week, Sarah had exams in math and in Spanish. On the math exam, the mean was µ = 30 with σ = 5, and Sarah had a score of X = 45. On the Spanish exam, the mean was µ = 60 with σ = 8, and Sarah had a score of X = 68. For which class should Sara expect the better grade?

a. Math

b. Spanish

c. The grades should be the same because the two exam scores are in the same location.

d. There is not enough information to determine which is the better grade.

8. Which of the following is a requirement for a random sample?

a. Every individual has an equal chance of being selected.

b. The probabilities cannot change during a series of selections.

c. There must be sampling with replacement.

d. All of the other 3 choices are correct.

9. A class consists of 10 males and 30 females. If one student is randomly selected from the class, what is the probability of selecting a male?

a. 10/30

B. 10/40

C. 1/10

d. 1/40

10. A class consists of 10 males and 30 females. A random sample of n = 3 students is selected. If the first two students are both females, what is the probability that the third student is a male?

a. 10/37 c. 10/40

b. 10/38 d. 8/38

11. Which of the following accurately describes the proportions in the tails of a normal distribution?

a. Proportions in both tails are positive.

b. Proportions in the right-hand tail are positive, and proportions in the left-hand tail are negative.

c. Proportions in the right-hand tail are negative, and proportions in the left-hand tail are positive.

d. Proportions in both tails are negative.

12. What proportion of a normal distribution is located in the tail beyond z = –1.00?

a. 0.841 c. –0.3413

b. 0.1587

d. –0.1587

13. What proportion of a normal distribution is located between the mean and z = 1.40?

a. 0.9192 c. 0.4192

b. 0.0808 d. 0.8384

14. What proportion of a normal distribution is located between the mean and z = –1.40?

a. 0.0808 c. –0.0808

b. 0.4192 d. –0.4192

15. What is the probability of randomly selecting a z-score less than z = –1.25 from a normal distribution?

a. 0.8944 c. 0.3944

b. 0.1056 d. 0.2112

16. A normal distribution has μ = 80 and σ = 10. What is the probability of randomly selecting a score greater than 90 from this distribution?

a. p = 0.8413 c. p = 0.3085

b. p = 0.1587 d. p = 0.6915

17. A normal distribution has a mean of µ = 70 with σ = 10. If one score is randomly selected from this distribution, what is the probability that the score will be greater than X = 82?

a. 0.7698 c. 0.1151

b. 0.3849 d. 0.8849

18. A normal distribution has a mean of µ = 100 with σ = 20. If one score is randomly selected from this distribution, what is the probability that the score will be less than X = 84?

a. 0.7881 c. 0.2881

b. 0.5762 d. 0.2119

19. A normal distribution has a mean of µ = 100 with σ = 20. If one score is randomly selected from this distribution, what is the probability that the score will have a value between X = 90 and X = 110?

a. 0.6915 c. 0.1915

b. 0.3085 d. 0.3830

20. A normal distribution has a mean of µ = 80 with σ = 20. What score separates the highest 15% of the distribution from the rest of the scores?

a. X = 59.2 c. X = 95

b. X = 100.8 d. X = 65

21. IQ scores form a normal distribution with µ = 100 and σ = 15. Individuals with IQs above 140 are classified in the genius category. What proportion of the population consists of geniuses?

a. 0.9962 c. 0.4962

b. 0.5038 d. 0.0038

22. What is the expected value of M?

a. It is the sample mean.

b. It is the sample standard deviation.

c. It is the mean of the distribution of sample means.

d. It is the standard deviation of the distribution of sample means.

23. What is the standard error of M?

a. It is the sample mean.

b. It is the sample standard deviation.

c. It is the mean of the distribution of sample means.

d. It is the standard deviation of the distribution of sample means.

24. For a population with µ = 80 and σ = 20, the distribution of sample means based on n = 16 will have an expected value of ____ and a standard error of ____.

a. 5; 80 c. 20; 20

b. 80; 5 d. 80; 1.25

25. A sample of n = 4 scores is selected from a population with μ = 40 with σ = 8, and the sample mean is M = 43. What is the standard error for the sample mean?

a. 8 c. 3

b. 4 d. 2

26. What symbol is used to identify the standard error of M?

a. µ c. σ

b. σM d. MM

27. A random sample of n = 60 scores is selected from a population. Which of the following distributions definitely will be normal?

a. The scores in the sample will form a normal distribution.

b. The scores in the population will form a normal distribution.

c. The distribution of sample means will form a normal distribution.

d. The sample, the population, and the distribution of sample means definitely will not be normal.

28. If a sample of n = 4 scores is obtained from a population with μ = 70 and σ = 12, what is the z- score corresponding to a sample mean of M = 73?

a. z = 0.25 c. z = 1.00

b. z = 0.50 d. z = 2.00

29. A random sample of n = 9 scores is selected from a normal distribution with μ = 80 and σ = 12. What is the probability that the sample mean will be between 76 and 84?

a. 0.9974 c. 0.3830

b. 0.6426 d. 0.2586

30. Which of the following accurately describes a hypothesis test?

a. A descriptive technique that allows researchers to describe a sample

b. A descriptive technique that allows researchers to describe a population

c. An inferential technique that uses the data from a sample to draw inferences about a population

d. An inferential technique that uses information about a population to make predictions about a sample

31. A hypothesis test involves a comparison of which two elements?

a. Research results from a sample and a hypothesis about a population

b. Research results from a population and a hypothesis about a sample

c. Research results from a population and a hypothesis about the population

d. Research results from a sample and a hypothesis about the sample

32. For a hypothesis test evaluating the effect of a treatment on a population mean, what basic assumption is made concerning the treatment effect?

a. If there is a treatment effect, it will increase the scores.

b. If there is a treatment effect, it will decrease the scores.

c. If there is a treatment effect, it will add (or subtract) a constant to each score.

d. If there is a treatment effect, it will multiply (or divide) each score by a constant.

33. Which of the following is directly addressed by the null hypothesis?

a. The population before treatment

b. The population after treatment

c. The sample before treatment

d. The sample after treatment

34. A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample is used for a hypothesis test, what does the null hypothesis (H0) say about the treatment?

a. The treatment causes a change in the scores.

b. The treatment adds a constant to each score.

c. The treatment multiplies each score by a constant.

d. The treatment has no effect on the scores.

35. A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample is used for a hypothesis test, what does the alternative hypothesis (H1) say about the treatment?

a. The treatment causes a change in the scores.

b. The treatment adds a constant to each score.

c. The treatment multiplies each score by a constant.

d. The treatment has no effect on the scores.

36. If a hypothesis test produces a z-score in the critical region, what decision should be made?

a. Reject the alternative hypothesis

b. Fail to reject the alternative hypothesis

c. Reject the null hypothesis

d. Fail to reject the null hypothesis

37. Which of the following is an accurate definition of a Type I error?

a. Rejecting a false null hypothesis

b. Rejecting a true null hypothesis

c. Failing to reject a false null hypothesis

d. Failing to reject a true null hypothesis

38. Which of the following is an accurate definition of a Type II error?

a. Rejecting a false null hypothesis

b. Rejecting a true null hypothesis

c. Failing to reject a false null hypothesis

d. Failing to reject a true null hypothesis

39. A researcher administers a treatment to a sample of participants selected from a population with µ = 80. If a hypothesis test is used to evaluate the effect of the treatment, which combination of factors is most likely to result in rejecting the null hypothesis?

a. A sample mean near 80 with α = .05

b. A sample mean near 80 with α = .01

c. A sample mean much different than 80 with α = .05

d. A sample mean much different than 80 with α = .01

40. A researcher conducts a hypothesis test to evaluate the effect of a treatment that is expected to increase scores. The hypothesis test produces a z-score of z = 2.27. If the researcher is using a one-tailed test, what is the correct statistical decision?

a. Reject the null hypothesis with α = .05 but not with α = .01

b. Reject the null hypothesis with either α = .05 or α = .01

c. Fail to reject the null hypothesis with either α = .05 or α = .01

d. Cannot answer without additional information

41. A sample of n = 9 individuals is selected from a population with μ = 60 and σ = 6, and a treatment is administered to the sample. After treatment, the sample mean is M = 63. What is the value of Cohen’s d for this sample?

a. 0.33

b. 0.50

c. 1.00

d. 2.00

42. On a psychology exam with = 76 and = 12, Tom scored 8 points below the mean, Mary had a score of X = 73, and Bill had a z-score of z = -0.50. Place these three students in order from lowest to highest score.

1. Student with lowest score 2. Student with middle score 3. Student with highest score

43. A normal distribution has a mean of = 80 with = 12. Find the following probabilities:

a. p (X > 83) c. p(X < 92)

b. p(X < 74) d. p(71 < X < 89)

44. Graduate Record Exam (GRE) scores for the psychology exam have a mean of 592 and a standard deviation of 101 (10 points)

a) What proportion of the test takers would have scored 650 or above?

b) What proportion of the test takers would have scored 700 or above?

c) What proportion of the test takers would have scored between 650 and 700?

d) If 10,000 individuals took the exam, how many would be expected to have scored 750 or above?

e) In working these problems, you began with an assumption about the distribution of GRE psychology scores. What is that assumption?

52. Research data indicate that adolescents, especially adolescent girls, experience a drop in self- esteem. To evaluate this result, a researcher obtains a sample of n = 9 adolescent girls, all 13 years old. A self-esteem test is given to each participant and the average score for the sample is M = 66. It is know that the distribution of self-esteem scores for the population of pre-teen girls is normal with = 75.

Subject | General |

Due By (Pacific Time) | 07/15/2014 02:00 pm |

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