大师作文网这是一道GRE数学概率题,题我读懂了,
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这是一道GRE数学概率题,题我读懂了,
For a certain probability experiment,the probability that event A will occur is 1/2 and the probability that event B will occur is 1/3 Which of the following values could be the probability that the event A ∪ B (that is,the event A or B,or both) will occur?Indicate all such values.A.1/3 B.1/2 C.3/4
For a certain probability experiment,the probability that event A will occur is 1/2 and the probability that event B will occur is 1/3 Which of the following values could be the probability that the event A ∪ B (that is,the event A or B,or both) will occur?Indicate all such values.A.1/3 B.1/2 C.3/4
由题意分三种情况：
1 A发生,B不发生 P=1/2×2/3=1/3
2.A不发生,B发生 P=1/2×1/3=1/6
3.A、B都发生 P=1/2×1/3=1/6
可见所以可能情况为1/3、1/6.
所以选A.
再问： 我也觉得是A，可是答案是BC，完全理解不了啊
1 A发生,B不发生 P=1/2×2/3=1/3
2.A不发生,B发生 P=1/2×1/3=1/6
3.A、B都发生 P=1/2×1/3=1/6
可见所以可能情况为1/3、1/6.
所以选A.
再问： 我也觉得是A，可是答案是BC，完全理解不了啊