Question

An industrial psychologist has a stress test that is used to determine the amount of stress that managers are under. A value of 80 or higher indicates “high stress.” The industrial psychologist believes that the managers at a large, profitable pharmaceutical firm are not under “high stress” and that the average stress index is less than 80 for managers of the company. A random sample of 50 managers is selected, and their stress index was recorded. Assume that the population standard deviation is 10.15. See the file “Stress Index for Managers”

Answer 1

If you perform a statistical test, try a one-sample z-test.

z = (sample mean - population mean)/(standard deviation divided by the square root of the sample size)

Population mean = 80
Sample mean = ? (I don't see one listed)
Standard deviation = 10.15
Sample size = 50

Once you have the z-test statistic, you can go from there to test your hypothesis.

I hope this helps.