Question: Usually people do not like waiting in line a long time for service. A bank manager does not want the variance of the waiting times for her customers to be greater than 4.0 square minutes. A random sample of 25 customers taken from this bank gave the variance of the waiting times equal to 8.3 square minutes.
a. Test at the 1% significance level whether the variance of the waiting times for all customers at this bank is greater than 4.0 square minutes. Assume that the waiting times for all customers are normally distributed.
b. Construct a 99% confidence interval for the population variance.