07prep-ps1第116题

116. 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)  3/4000

(B)  1/3600

(C)  9/2000

(D)  1/60

(E)  1/15

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