GMAT
题目
The probability of rain in Greg's town on Tuesday is 0.3. The probability that Greg's teacher will give him a pop quiz on Tuesday is 0.2. The event occur independently of each other.
Quantity A
The probability that either or both events occur
Quantity B
The probability that neither event occurs
解析
设A为“下雨”事件，B为“随堂测验”事件。
P(A)：0.3
P(B)：0.2
P(B|A)：0 …… 该概率表示在事件A已发生的条件下事件B发生的概率。由于两事件相互独立，因此该值为0。
A项：P(A)×(1-P(B)) + P(B)×(1-P(A)) + P(A)×P(B) = 0.14 + 0.24 + 0.06 = 0.44
B项：(1-P(A))×(1-P(B)) = 0.7×0.8 = 0.56
注：1-P(A)为事件A不发生的概率。
B项更大
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