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A psychology researcher who does work in creativity wants to determine whether her sample of 50-year-old adults (N = 150) differs statistically from the population of 50-year-olds in intelligence.

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These problems will follow the hypothesis-testing format that is similar to (but not exactly the same as) the one your textbook uses.
1. A psychology researcher who does work in creativity wants to determine whether her sample of 50-year-old adults (N = 150) differs statistically from the population of 50-year-olds in intelligence. For her sample, she calculates the following: Mean = 109, SD = 10. (Hint: By definition, the mean IQ of this population is 100 and the population standard deviation is 15. Another hint: Use the z-test here!)
A. Null hypothesis:
B. Alternative hypothesis:
C. Statistical test (You can't miss this one!):
D. Significance level (I'll pick it for you; alpha = .05)
E. Critical region for rejecting null hypothesis:
F. Calculate the statistic (please show your work):
G. Decision:
(5 points total)
2. A professor gives his class a final examination that he knows from years of experience yields a population mean of 84. His present class of 24 obtains a mean of 88 and a standard deviation of 8. Is he correct in assuming that the performance of the most recent class differs significantly from that of other classes? Use a one-tailed test here since the professor assumes that the class will score higher.
A. Null hypothesis:
B. Alternative hypothesis:
C. Statistical test:
D. Significance level (I'll pick it for you; alpha = .05)
E. Critical region for rejecting null hypothesis:
F. Calculate the statistic (please show your work):
G. Decision:
(6 points total)
3. An amateur researcher believes that the number of books owned is correlated with emotional intelligence (EQ). She randomly surveys 100 women and 100 men and finds r = .22. What does she conclude?
A. Null hypothesis:
B. Alternative hypothesis:
C. Statistical test:
D. Significance level (I'll pick it for you; alpha = .05)
E. Critical region for rejecting null hypothesis:
F. Calculate the statistic (please show your work):
G. Decision:

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