The Acme Super light bulb is known to have a useful life described by the density function
f (t) = .01e-.01t ,
where time t is measured in hours.
(a) Find the failure rate of this bulb
(b) Find the reliability of this bulb after 20 hours.
(c) Given that it lasts 20 hours, find the probability that the bulb lasts another 20 hours.
(d) Find the probability that the bulb burns out in the forty-first hour, given that it lasts 40 hours.