Wel, in this question you're gonna use combination
you need to combinate 20 participants in groups of four
so you make a combination:
Combination of 20, 4 =
Using the formula, you have:
20! / (20 - 4)! . 4!
20! / 16! . 4!
20 . 19 . 18 .17 . 16! / 16! . 4 . 3 . 2
20 . 19 . 18 . 17 / 4 . 3 . 2
simplifying:
5 . 19 . 3 . 17
4845
So the answer is 4845
I hope helped you
