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在连续两次摸球游戏的概率问题中,常见的两种摸球方式：有放回摸球和无放回摸球．下面向同学们介绍这两类题的解法．1．有放回基本模型：在一个口袋中装有m个红球和n个白球,这些球除颜色不同外．其他方面无差别．某人先从口袋中随机地摸出1个球,记下球的颜色后放回口袋中摇匀,然后再从中任意摸出1个球,求这两次摸出球的颜色是……的概率．在这个问题中,第一次摸球的对象是m+n个球,第二次摸球的对象仍然是这m+n个球．第一次摸到什么球对第二次摸球的结果无影响．
In the question of probability of touching the ball twice in a row, the two common ways of touching the ball are: putting back the ball and not touching the ball. Below to the students to introduce the solution of these two types of questions. 1. There are back to the basic model: In a pocket, there are m red balls and n white balls, except for the colors. No difference in other aspects. Someone randomly draws a ball out of his pocket, notes the color of the ball, shakes it back into his pocket, shakes it, and then draws a ball from it. Finding the color of the two balls is... Probability. In this question, the first time the ball is touched is m+n balls, and the second ball is still the m+n ball. What touched the ball for the first time has no effect on the result of touching the ball for the second time.