Chapter 11, Problem 26SE

Manufacture of Ball Bearings. Ball bearing manufacturing is a highly precise business in which minimal part variability is critical. Large variances in the size of the ball bearings cause bearing failure and rapid wearout. Production standards call for a maximum variance of .0001 inches². Gerry Liddy has gathered a sample of 15 bearings that shows a sample standard deviation of .014 inches.

1. a. Use α = .10 to determine whether the sample indicates that the maximum acceptable variance is being exceeded.
2. b. Compute the 90% confidence interval estimate of the variance of the ball bearings in the population.