The top selling Red and Voss tire is rated 70,000 miles means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 miles and a standard deviation of 6,400.
a. What is the probability that a tire wears out before 70,000 miles.
b. What is the probability that a tire last more than 100,000 miles?