題組內容

一、Suppose that explosion accidents on a particular city occur on the average about four times every year. If the occurrence of explosion accidents on this city constitutes a Poisson process,（Note：自然對數的指數次方值可以不必計算出來）
（二）Suppose further that and the proportion of causing fatal explosion accident is 1/4, find:

1. the p. m. f. of the occurrence of fatal explosion accidents, and（9分）