Please explain

Watch your cholesterol: The mean serum cholesterol level for U.S. adults was 203, with a standard deviation of 42 (the units are milligrams per deciliter). A simple random sample of 109 adults is chosen. Use the TI-84 calculator. Round the answers to four decimal places. Part 1 of 3 What is the probability that the sample mean cholesterol level is greater than 213? The probability that the sample mean cholesterol level is greater than 213 is Part 2 of 3 What is the probability that the sample mean cholesterol level is between 191 and 201? The probability that the sample mean cholesterol level is between 191 and 201 is Part 3 of 3 Would it be unusual for the sample mean to be less than 191? It (Choose one) v be unusual for the sample mean to be less than 191, since the probability is