作者Earadriewiel (ㄣ)
看板GMAT
标题[计量] PP-T1-PS116
时间Thu Sep 25 13:16:18 2008
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?
(A)3/40000
(B)1/3600
(C)9/2000
(D)1/60
(E)1/15
答案给A，请问一下有人可以说明一下算法吗 ?...感谢搂
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