feifei94

alsokkk

我怀疑这是一个笔误，这个从句应该是：when a randomly chosen
group of people is tested for cocaine use, the vast majority of those who test positive will be
people who have used cocaine.

xiaoniuren

DDD

bifan

那这道题选什么呢，我选的是C，不过同学给的打印答案上写的是B，求助NR！

kikisunflower

如果前面100 people who have not used cocaine 是randomly chosen得来的，100 people who have used cocaine也是randomly chosen得来的，而且后面a randomly chosen group of people量也足够大，作者的推理就是正确的。