A hospital is trying to cut down on emergency room wait times. It is interested in the amount of time patients must wait before being called back to be examined. An investigation committee randomly surveyed 70 patients. The sample mean was 1.5 hours with a sample standard deviation of 0.5 hours. Which distribution should you use for this problem? (Enter your answer in the form z or tdf where df is the degrees of freedom.) A quality control specialist for a restaurant chain takes a random sample of size 15 to check the amount of soda served in the 16 oz. serving size. The sample mean is 13.30 with a sample standard deviation of 1.53. Assume the underlying population is normally distributed. Find the 95% confidence interval for the true population mean for the amount of soda served. (Round your answers to two decimal places.)