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标题: [数学] Prep数学第158题编号15810-!-item-!-187;#058&010518 [打印本页]

作者: robert 时间: 2011-8-8 17:17 标题: Prep数学第158题编号15810-!-item-!-187;#058&010518

lzllfz问道:

Each of the 25 balls in a certain box is either red, blue, or white and has a number from 1 to 10 painted on it.
If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it?

(1)The probability that the ball will both be white and have an even number painted on it is 0.

(2)The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2.

我认为（2）是可以的因为可以抽到偶数的概率是可以算出来的设白球数量是N --------就是 N/25-12/25=0.2 求出N=17然后(17/25)*(12/25)就能够求出来了啊

我的解答：

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作者: NinaZ 时间: 2011-8-8 17:29

周老师辛苦啦~~~~~~~~

作者: guanglin405187 时间: 2011-8-26 22:21

hahahhahahha

作者: myice 时间: 2011-8-29 17:48

感谢分享

作者: smpowe 时间: 2011-9-6 19:28

good

作者: cloverlong 时间: 2014-8-12 23:01

这道题做错了，看看解答

作者: faytoo 时间: 2014-11-10 14:07

辛苦楼主咯...

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