The Manager of the Service Department of a Local Car

Multiple Choice

The manager of the service department of a local car dealership has noted that the service times of a sample of 30 new automobiles has a standard deviation of 6 minutes. A 95% confidence interval estimate for the standard deviation of the service times for all its new automobiles is _____.

A) 16.05 to 45.72
B) 4.78 to 8.07
C) 2.93 to 6.31
D) 22.83 to 65.06