Question: A machine produces pipes used in airplanes. The average length of the pipe is 16

inches. The acceptable variance for the length is .3 inches. A sample of 25 pipes

was taken. The average length in the sample was 15.95 inches with a variance of .4 inches.

a. Construct a 95% confidence interval for the population variance.

b. Use critical value approach to test that at the 5% level of significance, whether the

variance of the length of these 25 pipes significantly exceeds the specification.