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初中数学由数与代数、图形与证明、统计与概率、综合与实践四部分内容组成。其中统计与概率占据了比较重要的地位,在历年中考试题中都能见到其身影,并逐渐成为中考命题的热点之一。这部分试题往往难度不是很大,但由于审题不清,或者题意不理解,还是有很多学生会失分。下面就笔者在教学实践中发现学生在统计与概率问题中容易出现的一些常见的错误举例加以分析:例1一个家庭有3个孩子,求这个家庭中有2个男孩和1个女孩的概率。【错解】3个孩子共有四种情况:(男男男)、(男女女)、(男男女)、(女女女),所以P(男男女)=14.【错误分析】此题的错误类似于抛两枚硬币,误认为两个正面和一正一反发生的可能性是一样
Junior high school mathematics by the number and algebra, graphics and certification, statistics and probability, synthesis and practice composed of four parts. Statistics and probability occupy a more important position, in the calendar year examination questions can see its shadow, and gradually become one of the hot spots in the senior high school entrance examination. This part of the test is often not very difficult, but due to unclear exam questions, or the questions do not understand, there are still many students will lose points. Here are some common mistakes I found in my teaching practice that students are prone to in statistics and probability problems: Example 1 A family has 3 children and is asking for the probability of having 2 boys and 1 girl in this family. [Wrong solution] There are four cases of three children: (male male), (male and female), (male and female), (female and female), so P (men and women) = 14. [error analysis] The mistake is similar to throwing two coins, mistaken for the possibility of two positive and one positive and one negative reaction is the same