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Ash · 2022年10月12日

PA/B 和 PB/A

  1. CFA I
  2. Quantitative

NO.PZ2015120604000076

问题如下：


According to the above table, and we are informed that the performance of next day is good, what is the probability of today's performance is good?

选项：

A.

0.74.

B.

0.28.

C.

0.67.

解释：

C is correct.

We can use Bayes' formula to solve this problem.

A: today's performance is good.

B: next day's performance is good.

P(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=0.28

P(B)=0.4×0.7+0.2×0.3+0.4×0.2=0.42

P(A|B)=0.67

PA/B 和 PB/A 分别用文字描述麻烦解释一下

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1 个答案

星星_品职助教 · 2022年10月13日

同学你好，

P(A|B)：在B事件发生的条件下，A事件发生的概率。

P(B|A)：在A事件发生的条件下。B事件发生的概率。

事件A、B可以按照解题的目的自行定义，如答案解析中的：

A: today's performance is good.

B: next day's performance is good.

代入即可。

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