概率计算是中考命题的热点内容,下面结合2014年全国各地市中考题谈谈概率常用的计算方法.一、完全枚举法例1(2014年襄阳)从长度分别为2,4,6,7的四条线段中随机取二条,能构成三角形的概率是__.解析:从长度分别为2,4,6,7的四条线段中随机取三条,可能的结果为2,4,6;2,4,7;2,6,7;4,6,7.共4种.能构成三角形的是2,6,7;4,6,7.所以 Probability calculation is a hot topic in the middle school entrance exam.The following is a summary of the common probabilistic calculation methods of the city entrance examinations in 2014. First, enumerate law 1 (Xiangyang 2014) from the length of 2,4,6,7 Randomly take two of the four segments, the probability of forming a triangle is __ Analysis: From the length of 2, 4, 6, and 7 were randomly selected three lines, the possible results of 2,4,6; 2,4 , 7; 2, 6, 7; 4, 6, 7. A total of 4. Can form a triangle is 2,6,7; 4,6,7. So