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在概率问题中,一类涉及物品“取法”的问题一直是近几年中考的热点,较常见的有摸球、取卡片、选木棒、抽签等.解答这类问题的关键是弄清楚如何取,取几次,是放回还是不放回,下面举例说明.一、取一次且只取一个例1(2013年宁波)在一个不透明的布袋中装有3个白球和5个红球,它们除颜色不同外,其余均相同,从中随机摸出一个球,摸到红球的概率是().
Among the probabilistic problems, one of the problems related to the object “taking the law ” has always been a hot spot in recent years, and the more common ones are to touch the ball, take cards, pick sticks, draw lots, etc. The key to solving such problems is to get Clearly how to take, take a few times, is put back or not put back, the following example .One, take one and only take an example 1 (2013Nanbo) in an opaque bag with three white balls and five red In addition to the different colors of the balls, the rest are the same, and the probability of finding a red ball is () randomly obtained from a ball.