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标题: 一道数学题百思不得其解。。 [打印本页]

作者: dandanapple 时间: 2010-6-29 06:48 标题: 一道数学题百思不得其解。。

the probability of a is 60% and the probability of b is 50%, what is the most possible probability that neither a nor b would happen?

(a) 0.80
(b) 0.40
(c) 0.75
(d) 0.55
(e) 0.68

答案是0.4，百思不得其解，求大家帮忙呀！

作者: onedayling 时间: 2010-6-29 22:39

我猜测 A和B不是独立的，因此 A不发生0.4，B不发生０.５，　A,B均不发生的最大的possibility就是０.４了

作者: dandanapple 时间: 2010-6-30 06:27

有道理有道理！
这道题的关键是不是要理解0.6+0.5大于1，所以二者一定有交集呢？这样的话就容易想清楚了。

作者: xiangrui 时间: 2010-7-1 06:34

u might use the graph to help, it would be much easier for you to figure out the answer.
assume the A includes B , so you would get the "maximum possibility of neither A nor B" is 0.4
so here you only can choose 0.4 to be the answer.

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