And, in fact there's a technique of analysis used today that's called Rutherford back scattering where people actually saw that this is a means of identifying the substance, the sample.

事实上这是现在用的一种分析技术,称作卢瑟福背散射,就是人们实际上看到的那样,这是鉴别物质样品的一种方法。

麻省理工公开课 - 固态化学导论课程节选

But in our case, the probability of backscattering is going to be the number of balls that backscatter, and that's going to be divided by the total number of ping-pong balls.

用20除以132000，但现在背散射,的概率是被散射回来的小球，除以总的小球数,你们记得。

麻省理工公开课 - 化学原理课程节选

So, we have the probability here.

除了用背散射球数。

麻省理工公开课 - 化学原理课程节选