tongxun

redli：我的错！
正确公式如下：Pn，k = Cn，k * p^k *（1-p）^（n-k）
向广大G友道歉！现在才知道为什么数学只有50！

pgclt

What is 独立重复实验的公式? Could someone please summarize those formulas used in permutation and combination? or pls point to me where I can find them. I am a little confused about P&C questions, I used to be familiar with them when I took gre years ago, but forgot most of it. Thanks!!! email pgclt@yahoo.com.

tongxun

pgclt：
独立重复实验：如果在一次实验中某事件发生的概率是P，那么N次独立重复实验中这个事件恰好发生K次的概率。具体的公式就在你上面我的帖子里。

pgclt

tongxun, I got it. Thanks for your explanation. Are there other similar formulars for different Permuation&Combination scenarios? Thanks a lot.

tongxun

应该没有了。不知道求多边形的对角线数目公式：（Cn，2 ）-n 算不算。

pgclt

tongxun, that's a good one. （Cn，2 ）-n for 多边形的对角线数目. It definitely helps. Thanks!

michelle

redli的公式运用是对的.  
tongxue 的公式Cn,k *(p)n cifang *(1-p)de (n-k)cifang 中"(p)n cifang"
应该为"(p)k cifang"