An Internet based e-learning company has begun using new online statistics content to replace a textbook. Since the main competition is hardback textbooks, before the company decides what price to charge students for the new product, it wants to know the average price of all hardback statistics textbooks currently on the market. The research department at this e-learning company took a random sample of 20 such textbooks and collected information on their prices. The data could then be used to compute a confidence interval for the true mean price of hardback statistics textbooks. Assume the population of these textbook prices is normally distributed