試題詳解

246. Let X be the annual number of hurricanes hitting Florida, and let Y be the annual number of hurricanes hitting Texas. X and Y are independent Poisson variables with respective means 1.70 and 2.30.

 Calculate Var(X−Y| X+Y=3).
(A) 1.71
(B) 1.77
(C) 2.93
(D) 3.14
(E) 4.00