試題詳解

195. A machine has two parts labelled A and B. The probability that part A works for one year is 0.8 and the probability that part B works for one year is 0.6. The probability that at least one part works for one year is 0.9.

Calculate the probability that part B works for one year, given that part A works for one year.
(A) 1/2
(B) 3/5
(C) 5/8
(D) 3/4
(E) 5/6