Data obtained from the National Center for Health Statistics show that men between the ages of 20 and 29 have a mean height of 69.3 inches, with a standard deviation of 2.9 inches. A baseball analyst wonders whether the standard deviation of heights of major-league baseball players is less than 2.9 inches. The heights (in inches) of 20 randomly selected players are shown in the table.

(a) Verify that the data are normally distributed by drawing a normal probability plot.
(b) Compute the sample standard deviation.
(c) Test the notion at the α = 0.01 level of significance.