做题了做题了!# Joke - 肚皮舞运动s*j2017-01-11 08:011 楼一个黑盒子里面有6个球,每次拿两个,然后放回去。问:X次以后,what's the expected value of balls that have never been picked?怎么算啊?
l*s2017-01-11 08:015 楼定义P(n,X)为X次后,正好n个球没被取过的概率。E(n,X)=1*P(1,X)+2*P(2,X)+.。。+6*P(6,X)picked?【在 s*****j 的大作中提到】: 一个黑盒子里面有6个球,每次拿两个,然后放回去。: 问:X次以后,what's the expected value of balls that have never been picked?: 怎么算啊?
h*w2017-01-11 08:017 楼啥叫value of balls?balls当然是无价之宝,没有valuepicked?【在 s*****j 的大作中提到】: 一个黑盒子里面有6个球,每次拿两个,然后放回去。: 问:X次以后,what's the expected value of balls that have never been picked?: 怎么算啊?