标题: Anyone would like to show me how to solve these problems? Thanks a lot. [打印本页] 作者: redpot 时间: 2002-8-10 08:35 标题: Anyone would like to show me how to solve these problems? Thanks a lot.
1. A的发生概率为0.6，B发生的概率为0.5，问A,B都不发生的最大概率？
2. There are 6 groups in a room. Each group consists of 3 men. How many handshakes will there be if each man only shakes hands with people who are outside his group?作者: ssmcor 时间: 2002-8-10 12:40
As to 1, i am still a little bit confused. Does it mean that 0.5 possibility for both A and B occur at the same time? How about A with 0.6, B with 0.7, C with 0.8, then the possibility for all of them not occur? Is it 0.2?
Well, to 2, thank you very much. I got it. I can also get it by (C6,2)*(3*3).作者: tongxun 时间: 2002-8-12 02:42
So how about A with 0.6, B with 0.7, C with 0.8, then the possibility for all of them not occur? If they are dependent, the answer is 0.2. What if they are independent?作者: zhouxh 时间: 2002-8-13 21:53
答:
1.这道题本质上是一个集合的题。如果集合中只有A,B，且A包含B，都不发生的概率最大，0.4。
概率P=满足某个条件的所有可能情况数量/所有可能情况数量
性质 0<=P<=1
a1,a2为两两不相容的事件（即发生了a1，就不会发生a2)
P(a1或a2)=P(a1)+P(a2)
a1,a2不是两两不相容的事件，分别用集合A和集合B来表示
即集合A与集合B有交集，表示为A*B （a1发生且a2发生）
集合A与集合B的并集，表示为A U B （a1发生或a2发生）
则
P（A U B）= P(A)+P(B)-P(A*B)。。。。。。。。。。。。。。。。。公式2
还有就是条件概率：
考虑的是事件A已发生的条件下事件B发生的概率
定义：设A，B是两个事件，且P（A）>0,称
P（B|A）=P（A*B）/P（A）作者: redpot 时间: 2002-8-18 11:11
Thanks so much.
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