Question: a certain junior class has 1000 students and a certain senior class has 900 students . among these students , there are 60 siblings 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) 2 / 30000
C) 9 / 2000
D) 1 / 60
E) 1 / 15
Correct answer: B
Grade: 7 | Topic: Statistics and Probability | Difficulty: Hard | Standard: 7.SP.C.7