# probability

posted by
**jim**
.

The life of a certain type of device has an advertised failure of rate .01 per hour. The failure rate is constant and the exponential distribution applies.

(a)What is the mean time to failure?

(b)What is the probability that 150 hours will pass before a failure is observed?

(c)What is the probability that 3 of the next 6 failures observed will occur after 150 hours have passed?

(d)What is the probability that at most 3 failures will occur in 150 hours?