Question

A human resources manager wants to determine a confidence interval estimate for the mean test score
for the next office-skills test to be given to a group of job applicants. In the past, the test scores have been
normally distributed with a mean of 74.2 and a standard deviation of 30.9. Determine a 95% confidence
interval estimate if there are 30 applicants in the group.
A. 63.14 to 85.26
B. 68.72 to 79.68
C. 13.64 to 134.76
D. 64.92 to 83.48

Answer 1

You need to find the error in the problem. You should have a formula that determines error. You also need to transform the 95% confidence interval into a z score in order to solve. Mean plus your error, mean minus your error should give you the correct confidence interval for the problem. Does this help?