In a college,there are 20 major subjects and 40 minor subjects,these are divided into 20 groups of 2 students each , such that all the ways of dividing them into group are equally likely . A = no of...

In a college,there are 20 major subjects and 40 minor subjects,these are divided into 20 groups of 2 students each , such that all the ways of dividing them into group are equally likely .

A = no of groups having 1 major subject and 1  minor subject

Find the expectation E(X) of thesample A