作者skyhigh8988 (Aesthetic)
看板Math
标题Re: [机统] 应该是条件机率的问题
时间Tue Feb 15 10:58:27 2011
※ 引述《qazpoi753 (草间雨)》之铭言：
: 现在确定有65%的把握确定这个嫌犯有犯案。在审办的过程中，一个证人出面指证
: 嫌犯有85%的机会是左撇子。假设有23%的人口数都是左撇子，而嫌犯也是左撇子
: 请问在获得证人的资讯後，嫌犯犯案的机率变成多少？
: 因为怕自己翻译的不对，所以题目原文也贴上来
: A judge is 65% sure that a suspect has committed a crime. During the course of
: the trial a witness convinces the judge that there is an 85% chance that the
: criminal is left-handed. If 23% of the population is left-handed and the
: suspect is also left-handed, with this new information, how certain should
: the judge be of the guilt of the suspect?
: 请各位板友帮我解决这个问题
: 谢谢
很久没碰机率了 我个人觉得是这样
犯案的机率可能是
犯人是左撇子 且 被指证为左撇子 且他有犯罪
或是
犯人是右撇子 且 被指正为右撇子 且有犯罪
也就是 23% * 85% *65% + 77% * 15% * 65%
个人浅见
鞭小力点~~~`
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.116.117.15