試題詳解

124. In a given region, the number of tornadoes in a one-week period is modeled by a Poisson distribution with mean 2. The numbers of tornadoes in different weeks are mutually independent.
Calculate the probability that fewer than four tornadoes occur in a three-week period.
(A) 0.13
(B) 0.15
(C) 0.29
(D) 0.43
(E) 0.86