A machine produces pipes used in airplanes. The average length of pipe is 16 inches. The acceptable variance for 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. State the null and alternative hypotheses to be tested.
c. Compute the test statistic.
d. The null hypothesis is to be tested at the 5% level of significance. State the decision rule for the test using the critical value approach.
e. What do you conclude about the population variance?