試題詳解

142. The lifespan, in years, of a certain computer is exponentially distributed. The probability that its lifespan exceeds four years is 0.30. Let f(x) represent the density function of the computer’s lifespan, in years, for x ＞ 0. Determine which of the following is an expression for f(x).
(A)
(B)
(C)
(D)
(E)