国际顶尖MBA申请交流平台--TOPWAY MBA

标题: 数学一题谢谢大家 [打印本页]

作者: piggycandys 时间: 2010-8-7 06:33 标题: 数学一题谢谢大家

A certain junior class has 1000 students and a cetain senior has 800 students.Among these students , there are 60 sibling pairs,each consisting of 1 junior and 1 senior.If 1 student is to be selected random from each class, what is the possibilty that the 2 students selected will be a sibiling pair.
答案 3/40000
为什么

作者: daoyinger 时间: 2010-8-8 10:27

C(60,1)/C(800,1)*C(1000)
分母意思是从800人中random取一个，1000中random取一个的可能性
分子意思是取出来的至可能是60个sibiling pair，所以是60钟可能性

作者: piggycandys 时间: 2010-8-9 20:25

多谢了

欢迎光临国际顶尖MBA申请交流平台--TOPWAY MBA (http://forum.topway.org/)