4. A machine produces pipes used in airplanes. The average length of the pipe is 16 inches. The acceptable variance fer the length is [1.3 inches. A sample of 17 pipes was taken. The average length in the sample was 15.95 inches with a variance of {1.4 inches. Construct a 95% confidence interval for the population variance. (6%) State the null and alternative hypotheses to be tested. (6%} Compute the test statistic. (6%} The null hypothesis is to be tested at the 5% level of signicance. State the decision rule for the test using the critical value approach. (6%] e. What do you conclude about the population variance? (%} have