A certain junior class has 1000students 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 slected will be a sibling pair?
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2008-9-9 10:31:00
楼主