The age of a randomly selected individual in the USA is a Gaussian random variable with mean = 39.1 years and standard deviation = 5 years. (Report your numbers using Normal tables)

(a) Find the probability that a randomly selected individual is at least 50.

(b) Find the probability that a randomly selected individual is at least 30, and at most 50 years old.

(c) Find the age k > 0 so that the 90% of the population is at least k years old (k can be any positive number).