A study of 40 psychology teachers showed that they spent, on average, 12.6 minutes correcting a student's final term paper. Find the 90 percent confidence interval of the mean time for all psychology teachers correcting final term papers when the deviation is 2.5.

Answer 1

Formula:

CI90 = mean ± 1.645(s/√n)

mean = 12.6
s = 2.5
n = 40

Plug the values into the formula and calculate the interval.