# students and sub committees

• Sep 27th 2007, 04:21 PM
Mr_Green
students and sub committees
A.) From a committee of 15 students, in how many ways can a sub-committee of 3 students be selected?

B.) From a committee of 15 students, in how many ways can a chairsperson and then a secretary be elected?
• Sep 27th 2007, 08:08 PM
Jhevon
Quote:

Originally Posted by Mr_Green
A.) From a committee of 15 students, in how many ways can a sub-committee of 3 students be selected?

we want to choose 3 people from a group of 15, so the answer is 15 choose 3, or ${15 \choose 3}$

Quote:

B.) From a committee of 15 students, in how many ways can a chairsperson and then a secretary be elected?
$_{15}P_2 = 15 \cdot 14$, since there are 15 ways to choose the chair, and for each of those ways, there are 14 ways to choose the secretary