GMAT
题目
The probability that Gary will eat eggs for breakfast on any given day is . The probability that Gary will eat cereal for breakfast on any given day is . Gary never has both eggs and cereal for breakfast on the same day.
Quantity A
Probability that Gary eats eggs or cereal for breakfast on a particular day
Quantity B
1
解析
这里有两个事件：
事件A：吃鸡蛋，P(A)=3/7
事件B：吃麦片，P(B)=4/7
事件A与B同时发生：既吃鸡蛋又吃麦片，P(A and B)=0
P(A or B)=P(A)+P(B)-P(A and B)
=3/7+4/7-0=1
因此P(A or B)=1，选项C正确。
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