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一道GMAT数学题Acertainjuniorclasshas1,000studentsandacertainseniorclasshas800students.Amongthesestudents,thereare60siblingpairs,eachconsistingof1juniorand1senior.Ifstudentistobeselectedatrandomfromeachcla
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一道GMAT数学题
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 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)3/40,000
(B)1/3,600
(C)9/2,000
(D)1/60
(E)1/15
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 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)3/40,000
(B)1/3,600
(C)9/2,000
(D)1/60
(E)1/15
▼优质解答
答案和解析
从这些学生中选两人每班选一人的可能情况数：1000*800
从sibling pair中选一对的可能数：60
概率就是3/40000
从sibling pair中选一对的可能数：60
概率就是3/40000
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