Jones is the chairman of a committee. in how many ways can a committee of 5 be chosen from 10 people given that jones must be one of them?

Since Jones is mandatory, you have 9 people to choose from for the second seat, then 8 for the third, 7 for the fourth, and finally 6 for the fifth.

So your equation is
1(Jones) • 9( possibilities left) •8( possibilities left)• 7( possibilities left)• 6( possibilities left)
Or

1 • 9 • 8 • 7 • 6
=
3,024 possible ways in which a committee of 5 can be chosen from 20 people given that Jones must be one of them.

I'm gonna have to say about 13 percent

That they are numbers and related to each other.