試題詳解

93. The number of workplace injuries, N, occurring in a factory on any given day is Poisson distributed with mean λ. The parameter λ is a random variable that is determined by the level of activity in the factory, and is uniformly distributed on the interval [0, 3].
 Calculate Var(N).
(A) λ
(B) 2 λ
(C) 0.75
(D) 1.50
(E) 2.25