Help me with this question

A class survey in a large class for first-year college students asked, "About how many hours do you study during a typical week?\" The mean response of a random sample of 484 students was 13.7 hours. Suppose that we know that the study time follows a Normal distribution with standard deviation 0 = 1 1 hours in the population of all rst-year students at this university. a] Give a 98% condence interval for the mean study time of all rst-year students. There were actually 4-85 responses to the class survey. One student claimed to study 10,000 hours per week. We know he's joking, so we left out this value. If we did a calculation without looking at the data, we would get the sample mean of 35.2 hours for all 4-85 students. b] What is the 98% confidence interval for the population mean? Continue to use 0' = 11. (3] Compare your answers in a] and b]