11.53 [EX11-53] The weights (x) of 300 adult males were determined and used to test the hypothesis that the weights were normally distributed with a mean of 160 lb and a standard deviation of 15 lb. The data were grouped into the following classes.

Observed Observed Weight (x) Frequency Weight (x) Frequency x  130 7 160 x  175 102 130 x  145 38 175 x  190 40 145 x  160 100 190 and over 13 Using the normal tables, the percentages for the classes are 2.28%, 13.59%, 34.13%, 34.13%, 13.59%, and 2.28%, respectively. Do the observed data show significant reason to discredit the hypothesis that the weights are normally distributed with a mean of 160 lb and a standard deviation of 15 lb? Use   0.05.

a. Verify the percentages for the classes.

b. Solve using the p-value approach.

c. Solve using the classical approach.