4. A 2018 study of the time spent on the phone to get information from the IRS (Internal Revenue Service) call-in center found that, for a sample of 41 3 people, the average time spent waiting on \"hold\" before they could speak to a representative was 19.8 minutes with a standard deviation of 11.5 minutes. (20 pts) a. Calculate a 95% condence interval for the mean time spent waiting on \"hold\" for all callers to the IRS call-in center at that time. b. Without doing any complicated calculations, do you think it would be unusual for someone to have had a wait time on the phone of 30 minutes? 0. Estimate the sample size required to be able to estimate the value for the population mean wait time on the phone, u, to within a margin of error of 3 minutes with a 95% condence. Hint: use the sample standard deviation given in the problem as an estimate of the population standard deviation, 0