The mileage (in thousands of miles) that car owners get with a certain kind of radial tire is a random variable having an exponential distribution with θ = 40. Find the probabilities that one of these...

The mileage (in thousands of miles) that car owners
get with a certain kind of radial tire is a random variable
having an exponential distribution with θ = 40. Find the
probabilities that one of these tires will last
(a) at least 20,000 miles;
(b) at most 30,000 miles.