Question

From a club of 18 people, in how many ways can a group of five members be selected to attend a conference?

Answer 1

Selection here means you’ll use combination and not permutation.
Total number of members=18
Numbers to be selected=5
Therefore=18C5=n!/(n-r)!r!
=18!/(18-5)!5!
=18!/13!5!
=18x17x16x15x14x13!/13!x5x4x3x2x1
The 13 factorials will cancel out which will give
= 18x17x16x15x14\ 5x4x3x2x1
=1,028,160/120
=8,568ways.