Yearly demand on a supplier for a given item has been 10 in the past,and demands seem to be distriburted as a negative binomial random variable with parameters r=2 and p=0.2.An inventory manager stocks 8 items for the coming year .what is the probability that he will not be able to supply the demand this year?
(註:希望用中文解釋這條題目的意思 ~)
負二項分配
2009-12-02 10:14 pm
回答 (1)
2009-12-03 4:08 am
✔ 最佳答案
資料顯示公司的其中一項貨品上年有10件的需求量。此一貨品的需求量服從負二項分配。r=2,p=0.2。假設公司經理只是儲存8件貨品。求他不能滿足需求量的概率。基本上無可能用二項分配計到精確解﹐只可以由正態分佈近似。
此二項分配的平均數=10,變異數=40
P(X>8-0.5)
=P(Z>(2.5-10)/sqrt(40))
=P(Z>-0.3953)
~1-0.346
~0.654
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091202000051KK02520