Note: If you use a calculator for confidence intervals, you do not need to show work for the confidence interval itself (part a and part b), but should show work for other aspects such as the margin of error. 2. Suppose that in a sample of 28 Moraine Valley students, the mean amount of time they say they spend studying for classes each week is 8.6 hours with a standard deviation of 1.3 hours. a) Calculate a 99% confidence interval for the mean amount of time all Moraine Valley students spend studying for classes each week. b) Interpret your interval (see notes about interpretation of intervals before answering this) What type of interval did you use for part (a) (z-interval, t-interval, 1-prop-z-interval). Why? d) What is the margin of error associated with your estimate?