求和的问题,不论是用初等方法还是用分析的是相当困难的。但是利用概率计算的基本方法却可以比较容易地达到求和的目的。下面介绍这个方法。 现在提出如下的一个问题。 计算在下述条件下得到奖励的机会:从一个装有一个优质零件和一个次等零件的容器里,凭借对零件优劣特点的了解,两次取出零件(每次取出之后再放回,且零件型号相同),如果两次取出的是优质零件, The question of summation is very difficult whether it is using the elementary method or the analysis. However, the basic method of using probability calculation can easily achieve the goal of summation. The following describes this method. Now raise the following question. Calculate the chance to be rewarded under the following conditions: From a container with a high-quality part and a second-grade part, with the knowledge of the characteristics of the parts, remove the parts twice (replace them after each removal, and The same model number) if you take out two parts with good quality,