在一些概率的计算问题中,常会涉及多重变量,彼此紧密联系,使学生剪不断,理还乱,感到难以下手.解决此类问题的关键一是在诸多变量中确定基本变量(由试验直接产生,并引起其他变量变化的变量)及其分布列,二是理清其他相关变量与基本变量的关系,从而借助基本变量的分布列来解决问题.现举数例共同探讨. In the calculation of some probabilistic problems, multiple variables are often involved, and they are closely related to each other. This makes it difficult for the students to cut and manage. It is difficult to start. The key to solving such problems is to determine the basic variables in many variables. , And cause other variables to change the variable) and its distribution column, the second is to sort out the relationship between other relevant variables and basic variables, so as to solve the problem with the distribution of the basic variables. Several examples are discussed together.