Suppose the average length of stay in a chronic disease hospital of a certain type of patient is 60 days with a standard deviation of 15. If it is reasonable to assume an approximately normal distribution of lengths of stay, find the probability that a randomly selected patient from this group will have a length of stay:

(a) Greater than 50 days

(b) Less than 30 days

(c) Between 30 and 60 days

(d) Greater than 90 days

]==4.7.5 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