HDL is the “good” cholesterol. The higher a person’s HDL level, the lower the person’s risk of heart attack and stroke will be. In a study of 1541 men in their twenties, the men’s HDL cholesterol levels are approximately normally distributed with mean 47 mg/dl and standard deviation 12.5 mg/dl.
a. A man has low HDL (higher risk) if his HDL reading is less than 40 mg/dl (Source: American Heart Association). Find the probability that a man randomly selected from the 1541 men has low HDL.
b. A man has high HDL (lower risk) if his HDL reading is greater than 60 mg/dl (Source: American Heart Association). Find the probability that a man randomly selected from the 1541 men has high HDL.
c. Find the probability that a man randomly selected from the 1541 men has an HDL reading between 40 and 60 mg/dl.
d. Find the number of men in the study who have HDL readings between 40 and 60 mg/dl.