Refer to Data Set 21 in Appendix B for the axial loads (in pounds) of the aluminum cans that are 0.0109 in. thick.

a. Enter the observed frequencies in the above table.

b. Assuming a normal distribution with mean and standard deviation given by the sample mean and standard deviation, use the methods of Chapter 6 to find the probability of a randomly selected axial load belonging to each class.

c. Using the probabilities found in part (b), find the expected frequency for each category.

d. Use a 0.01 significance level to test the claim that the axial loads were randomly selected from a normally distributed population. Does the goodness-of-fit test suggest that the data are from a normally distributed population?

Axial load Frequency Less than 239.5 239.5-259.5 259.5-279.5 More than 279.5