PSY 429 Experimental Psychology
Class Exercise #2
Standard Scores (z scores)
PSY 429 Experimental Psychology
Class Exercise #2
Standard Scores (z scores)
1. What is the mean and standard deviation of a z-score distribution?
2. What is the z-score formula for a population?
3. What is the z-score formula for a sample?
4. A distribution of general psychology test scores has a mean of m = 60 and a standard deviation of s = 4. What is the z-score for Scott who received a 66? (Assume the distribution of test scores was normal.)
5. What proportion of scores lies above Scott's score of 66?
6. The distribution of SAT verbal scores for high school seniors has a mean of m = 500 and a standard deviation of s = 100. Joe took the SAT and scored 430 on the verbal subtest. What is the z-score which corresponds to Joe's score of 430?
a. What percentage of people fell below Joe?b. What percentage of people fell above Joe?
7. Given a normally distributed variable with a m = 50 and a s = 10, what proportion of scores falls below a score of 30?
8. Given a normally distributed variable with a m = 50 and a s = 10, what proportion of scores falls between a score of 40 and a score of 55?
9. Given a normal distribution of a sample with a M = 48 and a S = 10 and an n = 300, find the number of cases that would fall below a score of 44.
10. Given a normally distributed variable with a M = 50 and a S = 10, what proportion of scores falls between a score of 35 and a score of 40?
11.Find the score that separates the upper 20% from the lower 80% if the mean is 50 and the standard deviation is 10.
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