In a random sample of 29 people, the mean commute time to work was 31.2 minutes and the standard deviation was 7.1 minutes. Assume the population is normally distributed and use a tdistribution to construct a 95% confidence interval for the population mean mu . What is the margin of error of mu ? Interpret the results. The confidence interval for the population mean mu is (Round to one decimal place as needed.) The margin of error of mu is nothing