8. The manager of the service department of a local car dealership has noted that the service times of a sample of 15 new automobiles has a standard deviation of 4 minutes. A 95% confidence interval estimate for the variance of service times for all their new automobiles is: (D)

A. 4.231 to 26.8533

B. 5.222 to 29.794

C. 6.304 to 33.584

D. 8.576 to 39.796

E. None of the above

The answer is D but I need help with the steps. Please show steps.