A certain junior class has 1,000 students and a certain senior class has 800 students. Among these students, there are 40 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 at will be a sibling pair?  Options:
A) 3/40,000
B) 1/3,600
C) 1/20,000
D) 1/60
E) 1/15
Total number of ways of choosing one student from each group is = 800 * 1000   Number of cases in which a sibling pair will be got is = 40   Thus the probability that the 2 students selected will be a sibling pair is   = 40 /(800 * 1000)   = 1/20,000   1/20,000
<result>C</result>
A certain junior class has 1,000 students and a certain senior class has 800 students. Among these students, there are 40 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 at will be a sibling pair?