4. Some Auto Insurance Company's customers sometimes have to wait a long time to speak to a customer service representative when they call regarding disputed claims. A random sample of 24 such calls yielded a mean waiting time of 23 minutes with a standard deviation of 6 minutes. Assume that such waiting times for the population follow a normal distribution. a) What distribution do you need to use to construct a confidence interval? Why? b) Comment on the shape of sampling distribution of x. Is it skewed to the right, to the left, or normal? Find standard deviation of sampling distribution of x. c) Construct a 99% confidence interval for the population mean of such waiting times