If the total cholesterol values for a certain population are approximately normally distributed with a mean of 200 mg=100 ml and a standard deviation of 20 mg=100 ml, find the probability that an individual picked at random from this population will have a cholesterol value:

(a) Between 180 and 200 mg=100 ml

(b) Greater than 225 mg=100 ml

(c) Less than 150 mg=100 ml

(d) Between 190 and 210 mg=100 ml