High school math probability question:3 boys, 3 girls, choose 3 people to go to a speech contest

Choose 3 out of 6***There are C6'3=20 choices.

1, there is no girl, then all boys, 3 all go, so there is only one way to choose, so the result is 1/20.

2, there is a boy before, from the three boys inside the election there are 3 kinds of selection, there are still short of two girls, the election of the two girls there are C3'2 = 3 kinds of ***3x3 = 9 kinds of so the results of 9/20.

3. Same as 2, except that the men and women are interchanged.