A research scientist reports that mice will live an average of 40 months when their diets are

Question:

A research scientist reports that mice will live an average of 40 months when their diets are sharply restricted and then enriched with vitamins and proteins. Assuming that the lifetimes of such mice are normally distributed with a standard deviation of 6.3 months, find the probability that a given mouse will live

(a) More than 32 months;

(b) Less than 28 months;