The life expectancy (in years) of a microwave oven is a continuous random variable with probability density function
(A) Find the probability that a randomly selected microwave oven lasts at most 6 years.
(B) Find the probability that a randomly selected microwave oven lasts from 6 to 12 years.
(C) Graph y=f(x) for [0, 12] and show the shaded region for part (A).