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中学数学课中的《概率与统计》部分是以往没有讲过的新内容。教师还比较不熟悉,讲授概率题的解法也感到吃力。本文就此问题谈谈自己的点滴体会,供参考。一、如何思考解一道概率题,一般作如下考虑: 首先,分清题中有哪些事件;哪些事件是已知的,哪些事件是未知的(即所要求的事件)。其次,将这些事件字母化,这可使叙述方便简捷。然后,分析这些事件之间的关系。这样,就可以使用已知事件把未知事件表示出来。最后,根据上述分析,采用相应的公式进行计算,得出所求事件的概率。例1.一批产品共100件,其中有5件次品.现从中任抽取50件,问至少有一件次品的概率是多少?
The “Probability and Statistics” section in the middle school mathematics class is a new content that has not been mentioned before. The teacher is still relatively unfamiliar and the solution to the problem of probabilistic questions is also difficult. This article talks about his own experience on this issue for your reference. First, how to think about a solution to a probability question is generally considered as follows: First, distinguish which events are in the question; which events are known and which are unknown (that is, the requested event). Second, these events are alphabetized, which makes the narrative convenient and simple. Then, analyze the relationship between these events. In this way, unknown events can be represented using known events. Finally, based on the above analysis, the corresponding formula is used for calculation, and the probability of the requested event is obtained. Example 1. A total of 100 products in a batch, including 5 defective products. Now extract 50 from them. What is the probability of having at least one defective product?