Of the bolts manufactured for a certain application, 90% meet the length specification and can be used immediately, 6% are too long and can be used after being cut, and 4% are too short and must be scrapped.
(a) Find the probability that a randomly selected bolt can be used (either immediately or after being cut).
(b) Find the probability that fewer than 15 out of 20 bolts can be used.
(c) Find the probability that more than 12 but fewer than 18 out of 20 bolts can be used.
(d) How many bolts are expected to be used out of 50 bolts.