作者cugir (乌拉拉 噜勒勒)
看板Grad-ProbAsk
标题Re: [理工] [机率]-机率
时间Wed Oct 7 11:05:57 2009
※ 引述《AAJJBurnett (叫我投手)》之铭言：
: 1.Suppose there are 3 defective items in a lot of 50 items. A sample
: of size 10 is taken at random and without replacement. Let X denote the
: number of defective items in the sample. Find the probability that the
: sample contains
: (a)Exactly 1 defective item
: (b)At most 1 defective item
(a)
C3取1 * C47取9
---------------
C50取10
(b)
C3取0 * C47取10 C3取1 * C47取9
--------------- + ----------------
C50取10 C50取10
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1F：→ johanwu0313:这一题是HG吗? 10/08 18:09
2F：→ cugir:没错.. 10/08 18:40