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 1751 women in their twenties, the women’s HDL cholesterol levels are approximately normally distributed with mean 55 mg/dl and standard deviation 14.8 mg/dl.
a. A woman has low HDL (higher risk) if her HDL reading is less than 50 mg/dl (Source: American Heart Association). Find the probability that a woman randomly selected from the 1751 women has low HDL.
b. A woman has high HDL (lower risk) if her HDL reading is greater than 60 mg/dl. Find the probability that a woman randomly selected from the 1751 women has high HDL.
c. Find the probability that a woman randomly selected from the 1751 women has an HDL reading between 40 and 60 mg/dl.
d. Find the number of women in the study who have HDL readings between 40 and 60 mg/dl.