Ch. 5 Quiz 5 (PSYC 2013, NWACC)

Q: For a population with m = 70 and s = 8, what is the z-score corresponding to X = 82?

+1.50

Q: For a population with m = 40 and s = 8, what is the z-score corresponding to X = 34?

-0.75

Q: A sample of n = 20 scores is transformed into z-scores. What is the mean for the set of 20 z-scores?

0

Q: For any distribution, what is the z-score corresponding to the mean?

0

Q: A population of scores has m = 80. In this population, a score of X = 86 corresponds to z = +2.00. What is the population standard deviation?

3

Q: A distribution with m = 35 and s = 8 is being standardized so that the new mean and standard deviation will be m = 50 and s = 10. In the new, standardized distribution, your score is X = 45. What was your score in the original distribution?

X=31

Q: Using z-scores, a population with m = 37 and s = 6 is standardized so that the new mean is m = 50 and s = 10. After the standardization, one individual has a score of X = 55. What was this individual's score in the original distribution?

X=40

Q: In a population with s = 8, a score of X = 44 corresponds to a z-score of z = -0.50. What is the population mean?

m=48

Q: You have a score of X = 65 on an exam. Which set of parameters would give you the best grade on the exam?

m=60 and s=5

Q: A population has m = 50. What value of ó would make X = 55 an extreme value out in the tail of the distribution?

s=1

Q: A population with m = 85 and s = 12 is transformed into z-scores. After the transformation, what is the standard deviation for the population of z-scores?

s=1

Q: In a sample with M = 40 and s = 8, what is the z-score corresponding to X = 38?

z= -0.25

Q: A sample of n = 20 scores has a mean of M = 45 and a standard deviation of s = 8. In this sample, what is the z-score corresponding to X = 57?

z=1.50

T/F: A positive z-score always corresponds to a score that is greater than the mean.

True

Q: A sample with M = 85 and s = 12 is transformed into z-scores. After the transformation, what are the values for the mean and standard deviation for the sample of z-scores?

M=0 and s=1

Q: For a sample of n = 100 scores, X = 45 corresponds to z = 0.50 and X = 52 corresponds to z = +1.00. What are the values for the sample mean and standard deviation?

M=38 and s=14

Q: Last week Tim got a score of X = 54 on a math exam with m = 60 and s = 8. He also got X = 49 on an English exam with m = 55 and s = 3, and he got X = 31 on a psychology exam with m = 37 and s = 4. For which class should Tim expect the best grade?

Math

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

Math

Q: For a sample of n = 30 scores, a score that is 6 points above the mean has a z-score of z = 1.50. What is the sample standard deviation?

4

Q: For a population with m = 40 and s = 8, what is the X value corresponding to z = 1.50?

52

Q: What position in the distribution corresponds to a z-score of z = -1.00?

Below the mean by a distance equal to 1 standard deviation

T/F: A score that is 6 points above the mean corresponds to a z-score of z = +0.50. For this population, the standard deviation is s = 3.

False

T/F: For a population with a mean of m = 40, a score of X = 37 corresponds to z = -0.50. The standard deviation for the population is s = 3.

False

T/F: For a population with m = 34, a score of X = 31 corresponds to z = -1.00. The standard deviation for the population is s = 6.

False

T/F: A professor standardizes exam scores so that all exams have m = 50 and s = 10. If the original scores from an exam have m = 42 and s = 6, then a student with an original exam score of X = 45 would receive a standardized score of X = 55.

True

T/F: A z-score of z = +1.00 always indicates a location exactly 1 standard deviation above the mean.

True

T/F: For a population of exam scores, a score of X = 83 corresponds to z = +0.50 and a score of X = 89 corresponds to z = +1.50. The population mean is m = 80.

True

T/F: For a population with a mean of m = 80, any score greater than 80 will have a positive z-score.

True

T/F: For a sample with a standard deviation of s = 10, a score with a deviation of +5 will have a z-score of z = 0.50.

True

T/F: If an entire population of N = 20 scores is transformed into z-scores, the set of 20 z-scores will have SS = 20.

True

T/F: If an entire population of N = 20 scores is transformed into z-scores, the set of 20 z-scores will have SX = 0.

True

T/F: In a population with s = 4, a score of X = 48 corresponds to z = 1.50. The mean for this population is m = 42.

True

T/F: On an exam with s = 6, Tom's score of X = 54 corresponds to z = -1.00. The mean for the exam must be m = 60.

True

Q: Under what circumstances is a score that is 15 points above the mean an extreme score relatively far from the mean?

When the population standard deviation is much smaller than 15