Baseballs vary somewhat in their rebounding coefficient. A baseball that has a large reb...

Baseballs vary somewhat in their rebounding coefficient. A baseball that has a large rebound coefficient will travel further when the same force is applied to it than a ball with a smaller coefficient. To achieve a game in which each batter has an equal opportunity to hit a home run, the balls should have nearly the same rebound coefficient .A standard test has been developed to measure the rebound coefficient of baseballs. A purchaser of large quantities of baseballs requires that the mean coefficient value be 85 units and the standard deviation be less than 2 units. A random sample of 81 baseballs is selected from a large batch of balls and tested. The data are summarized here.

a. Does the plot indicate any violation of the conditions underlying the use of the chi-square procedures for constructing confidence intervals or testing hypotheses about σ ?

b. Is there sufficient evidence that the standard deviation in rebound coefficient for the batch of balls is less than 2?

c. Estimate the standard deviation of the rebound coefficients using a 95% confidence interval.