Question

Use the standard normal distribution or the​ t-distribution to construct a 90​% confidence interval for the population mean. Justify your decision. If neither distribution can be​ used, explain why. Interpret the results. In a random sample of 13 ​people, the mean length of stay at a hospital was 6.9 days. Assume the population standard deviation is 2.1 days and the lengths of stay are normally distributed. Which distribution should be used to construct the confidence​ interval? A. Use a normal distribution because the lengths are normally distributed and sigma is known. B. Use a​ t-distribution because nless than30 and sigma is unknown. C. Use a​ t-distribution because the lengths are normally distributed and sigma is known. D. Use a normal distribution because ngreater than or equals30. E. Cannot use the standard normal distribution or the​ t-distribution because sigma is​ unknown, n less than 30​, and the days are not normally distributed

Answer 1