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)





答案:E
統計:A:0,B:0,C:0,D:0,E:0
難度:計算中