石破天和石中玉是双胞胎,因长得几乎一模一样,两个人又是同桌,同学们很难分清。新同学杨过来了,问他俩的名字,结果他们都说自己是石破天。老师过来说,已知他们俩一个人总是坐左边,一个总是坐右边,且右边说谎的概率是1/4,左边说谎的概率是1/5,问:石中玉坐左边的概率是多少?
If there is no information, we assume the probability of "石中玉坐左边" is 1/2. The only information we have is " 他们都说自己是石破天". So the conditional probability is 3/7. |
欢迎光临 珍珠湾ART (http://zzwav.com/) | Powered by Discuz! X3 |