Brake pads in a car need to be changed on after 7 years on average. The cost is normally distributed as N($350,$50).
a. What is the probability that the pads need to be changed in the first year?
b. What is the probability that a customer will have to replace the pads only once during a period of 10 years?
c. What is the probability that a customer does not pay in excess of $500 for a brake pad replacement over a period of 10 years?