Question

How many committees of 3 can be formed from a group of 9?

Answer 1

We can form `84` committees.

Explanation:

We can form `color(white)x^nC_r=(n(n-1)...(n-r+1))/(1*2*3*...*r)` committees of `r` from a group of `n`

Hence number of committees of size `3` that can be formed from a group of `9` members is

`color(white)x^9C_3`

= `(9*8*7)/(1*2*3)=84`