学过统计学的话，就不能如此计算概率吧？

（起码也要说明条件概率）

设全世界总人口为n，男性人口为m。

（1）在m中扣除年龄因素（可能出现“少女嫁老翁”，但不太可能出现男婴娶少女——估计没有人愿做童养媳），设m中满a岁的人口为m1

（2）在m1中扣除收入因素，设m1中年收入不低于y的人口为m2

……

每考虑一种因素，就可能（而非必然）减少一部分人（画几个圈圈，找找圈圈之间的关系）。

最后看看有多少人是“备选对象”。——当然，更要看，有多少同性在竞争这些备选对象。

显然，为实现以上统计，收集详细且真实的情报是首要的，但收集的过程也是自己衰老的过程。

P(A+B)=P(A)+P(B)-P(AB)

教授举了不恰当的例子。

不知道是不是我的概率没学好，总觉得哪里有点儿奇怪。

可是就算没错，其实这个逻辑也不太对，有这些优点也并不能说明他没有缺点，或者说什么叫做“如意”呢？是指有上述优点而没有任何缺点，还是指只要有上述的优点就可以有没有缺点无所谓呢？

This is an irrational example of Statistics, thought it is fun.

No one could encounter all his or her potential spouses. This is the way poeple do: get the first, if not fit, find the second, then if not fit, find the next and so continue finding util one who really becomes the spouse, or never get married. Even some people would have more than one girlfriend or boyfriend at the same time the method of finding spouses is basicly the same. Can you figure out the possibility of any combination of favorate traits?

Further, and because it is an Economics forum here, mathematic optimization process is normally not suited for social phenomena among which is the process of finding "optimal" spouses, as what the example implies.

However, I show respect to the professor whose heart's full of niceness to students with workmanship.