【正文】
ume that you live in a district of size 10 blocks by 10 blocks so that the total district is divided into 100 small squares. How likely is it that the square in which you live will receive no hits if the total area is hit by 400 bombs? 精品 精品 ? 用 X 表示落入該小區(qū)內(nèi)的炸彈數(shù),則 ? X~B(400,1/100) n=400, p=1/100 ? 因此 P(X=0)=(99/100)^400 ? 用 Poisson分布近似計(jì)算。 ? X近似服從參數(shù)為 4 =np=400*1/100的 Poisson 分布 ? 即 X~P(4) ? 因此 P(X=0)=exp(4) ? P(X=0)=(99/100)^400 ? 可以計(jì)算 (99/100)^400= ? exp(4)=