There are a total of 48 students in grade 10 charity.Twenty are boys and 28 are girls.S uppose that a team of 3 students is formed such that it is composed of a team leader,a secretary,and a spokesperson.What is the probability that a team formed is composed of a girl secretary?
Here is my solution, hope it can help :)
(28*47*46)/(48*47*46) = 7/12.
The idea is, choose the secretary first, which has 28 options. After that, we choose the other 2 positions by selecting the rest of people without any condition :)