第105页

习题2.2的第二小题
有人与你生日相同的概率有多大

改成

有且仅有一个人与你生日相同的概率有多大

原文描述：
You go to a party with 500 guests. What is the probability that exactly
one other guest has the same birthday as you? Calculate this exactly and
also approximately by using the Poisson PMF. ( For simplicity. exclude
birthdays on February 29 . )