Question: The dataset cholest on the companion website reports cholesterol levels of heart attack patients 2, 4, and 14 days after the heart attack. Data for days 2 and 4 were available for 28 patients. The mean difference (2 day - 4 day) was 23.29, and the standard deviation of the differences was 38.28. A histogram of the differences was approximately bell-shaped. Is there sufficient evidence to indicate that the mean cholesterol level of heart attack patients decreases from the second to fourth days after the heart attack? Use a= .01.