标题: prep 一道古典概率题 [打印本页] 作者: CD用户363773 时间: 2009-12-9 19:01 标题: prep 一道古典概率题 A certain junior class has 1,000 students and a certain senior class has 800 students. Among these students, there are 60 sibling pairs, each consisting of 1 junior and 1 senior. If 1 student is to be selected at random from each class, what is the probability that the 2 students selected will be a sibling pair?