作者wassili (咎由自取)
看板Statistics
标题[问题] 问一个期望值的问题
时间Fri Feb 17 21:41:41 2006
One of four different prizes was randomly put into each box of a cereal.
If a family decided to buy this cereal
until it obtained at least one of each of the four different prizes,
what is the expected number of boxes of cereal that must be purchased?
想了很久...试过很多种想法算出来都不对= ="
请教板上的高手了
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1F：推 mangogogo:折价卷问题 这之前就有人问过了 02/17 21:43
2F：→ mangogogo:1699 给你参考 02/17 21:44
3F：推 wassili:感谢.这类题型从正面去思考实在很难了解 02/17 22:34