The life (in miles driven) of a certain type of automobile tire is a normal random variable L, with L = 34; 000 and L = 4; 000.
(a) What is the probability that such a tire lasts over 40,000 miles?
(b) What is the probability that such a tire lasts between 30,000 and 35,000 miles?
(c) Given that such a tire has survived 30,000 miles, what is the conditional probability that it survives less than 40,000 miles?