Part variability is critical in the manufacturing of ball bearings. Large variances in the size of the ball bearings cause bearing failure and rapid wearout. Production standards call for a maximum variance of .0001 when the bearing sizes are measured in inches. A sample of 15 bearings shows a sample standard deviation of .014 inches.
a. Use α = .10 to determine whether the sample indicates that the maximum acceptable variance is being exceeded.
b. Compute the 90% confidence interval estimate of the variance of the ball bearings in the population.