A researcher drew a sample of 400 people, measured their IQs, and tested the null hypothesis that IQ = 100. The researcher obtained z = +3.00, which led her to reject the hypothesis (was 15.0). (a) What was the standard error of the mean?
(b) What was the mean of the sample?
(c) The test yielded a statistically significant outcome. Does it appear to be an important one? Explain.
(d) How much of a standard deviation did the discrepancy between X and hyp amount to?