The laser used in a Compact Disc player has a time to failure which follows an exponential distribution with a mean of 1250 hours of playing time.
a) Find the probability that the laser will fail within one year if it is used one hour every day.
b) Given that the last has already lasted 2 years, find the probability that it will last a total of 3 years.
Assume the Compact Disc player is used one hour every day.