you have 9 kittens for adoption, you can only afford to bring 3 home. how many different groups can you adopt?

Question

It is a counting problem.

Answer 1

To bring home 3 cats from a group of 9, you would be sampling where order does not matter. In other words, if you took home cat1/c2/c3 is the same as taking home c3/c2/c1. So you can solve using combinations instead of permutations.

 

9C3

= 9! / (6! * 3!)

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

= 84