The distribution of blood cholesterol levels in 14 - year - old boys is roughly normal; the mean is 165 milligrams of cholesterol per deciliter of blood and the standard deviation is 30.
Prob Z Value(s) (if more than one seperate them with an "and" answer rded to 4 decimals
a) between 120 and 200
bover 200
c) sample of 200, over 160
D) if 500 boys sample, over 170