求高手帮解概率题
问题描述：
求高手帮解概率题
Question 1.Customers arrive at a busy check-out counter of a large grocery store at an average rate of 6 per minute.It is assumed that number of customer arrivals follows Poisson distribution.
a.Find the probability that in any given minute there will be three or fewer arrivals.
b.Find the probability that there will be no less than 5 arrivals in two minute period
答
显然这里泊松分布的那个参数就是6,根据泊松分布的定义,有P（X=k）=(6^k)*[e^(-6)]/k!第一个问就是P=P(X=0)+P(X=1)+P(X=2)+P(X=3)把每一项都代入到上面的式子里,就能求出来了第二个问2分钟内,顾客少于5的概率：第一分...