機率問題－Bayes' Rule，計算機率多少？
2014-04-14 6:09 am
Males and females are observed to react differently to a given set of circumstances. It has been observed that 70% of the females react positively to these circumstances, whereas only 40% of males react positively. A group of 20 people, 15 female and 5 male, was subjected to these circumstances, and the subjects were asked to describe their reactions on a written questionnaire. A response picked at random from the 20 was negative. What is the probability that it was that of a male?
回答 (9)
2014-04-14 8:08 am
✔ 最佳答案
M :maleF : female
P : react positively
N : react negatively
P(F and N) = (15/20) x (1 - 70%) = 0.225
P(M and N) = (5/20) x (1 - 40%) = 0.15
P(N) = P(F and N) + P(M and N) = 0.225 + 0.15 = 0.375
P(M | N)
= P(M and N) / P(N)
= 0.15 / 0.375
= 0.4
參考: 土扁
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收錄日期: 2021-04-13 21:17:39
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20140413000010KK06537