試題詳解

107. Let X represent the number of customers arriving during the morning hours and let Y represent the number of customers arriving during the afternoon hours at a diner.
You are given:
i) X and Y are Poisson distributed.
ii) The first moment of X is less than the first moment of Y by 8.
iii) The second moment of X is 60% of the second moment of Y.
Calculate the variance of Y.
(A) 4
(B) 12
(C) 16
(D) 27
(E) 35