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苏·Xu · 2024年07月14日

概率

  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

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。

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品职助教_七七 · 2024年07月15日

嗨，从没放弃的小努力你好：


题目没有问题。问的就是条件概率，应理解为在“the performance of next day is good”的条件下，“today's performance is good”的条件概率是多少。

----------------------------------------------
虽然现在很辛苦，但努力过的感觉真的很好，加油！

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