珍珠湾ART

标题: a probability question [打印本页]

作者: HF: 时间: 2008-7-10 06:30
标题: a probability question

what is the expected number of random numbers, uniformally distributed from
0 to 1 needed for the sum to be greater than 1?

作者: 喝醉了的猫 时间: 2008-7-10 08:18
标题: 2 @。@

2 @。@

作者: idiot94 时间: 2008-7-10 08:58
标题: you probably meant for the # of IIDs... here

the independance is crucial.

作者: HF: 时间: 2008-7-10 16:44
标题: Yes, assume the random variables are independent

Yes, assume the random variables are independent

作者: ereaf 时间: 2008-7-11 02:36
标题: 3

E(xi)=0.5
n*E(xi)>1
n>3

作者: idiot94 时间: 2008-7-12 18:42
标题: both answers are good estimates of the correct

result :) The expectation is actually between 2 and 3. And it is a very familiar number to us :)

But this problem is actually harder than it looks. Needs some calculation and patience :)

欢迎光临珍珠湾ART (http://zzwav.com/)