(a) Is it plausible that the service times are normally distributed with a mean of 70 seconds ami a standard deviation of 20 seconds'.'
(b) Is it plausible that the service times are exponentially distributed with a mean of 70 seconds?
(c) Consider the null hypothesis that the median service time is no longer than 65 seconds. What statistic is used by the sign test procedure to test this null hypothesis? What is the p-value?
(d) Test the null hypothesis in part (e) using the signed rank test.
(e) Use the sign test and the signed rank test to obtain 95% confidence intervals on the median service time.