A machine produces pipes employed 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 sample was 15.95 inches with variance of .4 inches.
a. Develop a 95% confidence interval for the population variance.
b. Describe the null and alternative hypotheses to be tested.
c. Calculate the test statistic.
d. The null hypothesis is to be tested at 5% level of significance. Describe the decision rule for the test using the critical value approach.
e. What do you conclude about the population variance?