Question 1009917
mean is 27.05556
sx=9.17
n=18
Right off, the sample mean is less than the postulated mean, so there is insufficient evidence to show that the mean size class is more than 32 students.  This is with a one-tail test.  One-sided confidence intervals are tricky, but the two-sided is (20.788,33.323), as expected.  For this to have any chance of significance, the mean of the sample has to be greater than 32.