mathematics probability

Question

A committee consists of 5teachers from School A and 4 teachers form school B.Four teachers are randomly selected from the committee.

a) Find the probability that only 2 of the selected teachers are from school A

b) Find the probability that the numbers of selected teachers from school A and a school B are different

please give the step instead of simply the answer. Thank you for helping

Answer 1

You need the hypergeometric distribution to solve this problem.

In what follows _nC_r is the binomial coefficient of pick r from n.

A) ₅C_{2 * 4}C_{2 / 9}C₄

B) The answer is 1 - the answer in part A.