作者yitsung (夜冲弟)
看板Grad-ProbAsk
标题Re: [商管] [机率]-条件机率
时间Tue Feb 2 23:31:46 2010
※ 引述《locust0923 (柠檬优酪乳)》之铭言：
: 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 crimianl is left-handed .If 23% of the population is left-handed and
: the suspect is also left-handed, with this new information, how certain
: shoud the judge be of the guilt of the suspect?
: 大概知道它是要求条件机率，不过感觉给的条件不是很够
: 大概是我的题目理解差....希望有高手人帮忙一下
: 给个提示也可以，给个想法也可以，感激!!
P(嫌疑犯是凶手) = 0.65
P(嫌疑犯不是凶手) = 0.35
P(嫌疑犯是左撇子|嫌疑犯不是凶手) = 0.23
P(嫌疑犯是左撇子|嫌疑犯是凶手) = 0.85
0.65*0.85 1105
P(嫌疑犯是凶手|嫌疑犯是左撇子) = ---------------------- = ----------
0.35*0.23 + 0.65*0.85 1266
应该是这样吧，有错请指正
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◆ From: 58.114.138.177
1F：推 locust0923:谢谢!!P(嫌疑犯是左撇子|嫌疑犯不是凶手) = 0.23这地方 02/02 23:42
2F：→ locust0923:我想错了....以为题目给的是全部人左撇子的机率...= = 02/02 23:43
3F：→ locust0923:非常感激你的回答!! 02/02 23:43