问题如下图：
选项：
A. 
B. 
C. 
解释：
分母上表示所有第二天是good的概率，那为什么分子是0.4*0.7？
NO.PZ2015120604000076问题如下 Accorng to the above table, anwe are informeththe performanof next y is goo whis the probability of toy's performanis goo A.0.74.B.0.28.C.0.67. C is correct.We cuse Bayes' formula to solve this problem.toy's performanis goonext y's performanis gooP(A|B)=P(B|A)*P(A)/P(B)=0.7×0.4/(0.4×0.7+0.2×0.3+0.4×0.2)P(B|A)*P(A)=0.7×0.4=0.28P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42P(A|B)=0.67 我的理解贝叶斯公式是P（A｜B）=P（B｜A）*P（A）/P（B），P（B｜A）=0.4*0.7，P（B）=0.4*0.7+0.2*0.3+0.4*0.2=0.42，P（A）=0.4，但是这样算下来跟答案不一样，是不是P（A）错了？
NO.PZ2015120604000076 问题如下 Accorng to the above table, anwe are informeththe performanof next y is goo whis the probability of toy's performanis goo A.0.74. B.0.28. C.0.67. C is correct.We cuse Bayes' formula to solve this problem.toy's performanis goonext y's performanis gooP(A|B)=P(B|A)*P(A)/P(B)=0.7×0.4/(0.4×0.7+0.2×0.3+0.4×0.2)P(B|A)*P(A)=0.7×0.4=0.28P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42P(A|B)=0.67 这个题目有问题吧？题目的意图是想考察条件概率，但是问法并不是，问的就是一个独立事件的概率。
NO.PZ2015120604000076 问题如下 Accorng to the above table, anwe are informeththe performanof next y is goo whis the probability of toy's performanis goo A.0.74. B.0.28. C.0.67. C is correct.We cuse Bayes' formula to solve this problem.toy's performanis goonext y's performanis gooP(A|B)=P(B|A)*P(A)/P(B)=0.7×0.4/(0.4×0.7+0.2×0.3+0.4×0.2)P(B|A)*P(A)=0.7×0.4=0.28P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42P(A|B)=0.67 这个题用贝叶斯公式怎么画图啊
NO.PZ2015120604000076 问题如下 Accorng to the above table, anwe are informeththe performanof next y is goo whis the probability of toy's performanis goo A.0.74. B.0.28. C.0.67. C is correct.We cuse Bayes' formula to solve this problem.toy's performanis goonext y's performanis gooP(A|B)=P(B|A)*P(A)/P(B)=0.7×0.4/(0.4×0.7+0.2×0.3+0.4×0.2)P(B|A)*P(A)=0.7×0.4=0.28P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42P(A|B)=0.67 如题
NO.PZ2015120604000076 问题如下 Accorng to the above table, anwe are informeththe performanof next y is goo whis the probability of toy's performanis goo A.0.74. B.0.28. C.0.67. C is correct.We cuse Bayes' formula to solve this problem.toy's performanis goonext y's performanis gooP(A|B)=P(B|A)*P(A)/P(B)=0.7×0.4/(0.4×0.7+0.2×0.3+0.4×0.2)P(B|A)*P(A)=0.7×0.4=0.28P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42P(A|B)=0.67 老师，这个式子完全没看懂，麻烦一下每一步。谢谢
