Susie · 2023年03月30日

这题好容易弄混出错，有啥记忆方式吗？

1. CFA I
2. Quantitative

NO.PZ2022071202000028

问题如下：

Question The probability of Event A is 40%. The probability of Event B is 60%. The joint probability of AB is 40%. The probability (P) that A or B occurs, or both occur, is closest to:

选项：

A.40%. B.84%. C.60%.

解释：

Solution

C is correct. P(A or B) = P(A) + P(B) - P(AB) = 0.40 + 0.60 - 0.40 = 0.60 or 60%.

A is incorrect because it uses only the joint probability of 40%.

B is incorrect; it is obtained by adding 0.60 and 0.24 (0.60 × 0.40) = 0.84.