Question

In how many ways can a teacher arrange 6 students in the front row of a classroom with a total of 20 students?

Answer 1

This is a combination of 20 studants, 6 to 6:

$C_{2,6}=\frac{20!}{(20-6)!6!}=\frac{20!}{14!6!}=\frac{20.19.18.17.16.15.14!}{14!.6.5.4.3.2.1}=38,760 \ ways$