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. 答案是e 但是我觉得（2）单独也是可以的吧，主要是我觉得题目没有说清楚 has a number from 1 to 10 是嘛意思，如果是1-10再1-10再1-5涂完25个球，那就可以求出even的概率了吧？
谢谢！！！
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发表于 2017-8-22 15:50:14
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