Question

a class is given 20 questions to study. five of these will make up the their test. how many combinations of the 5 questions can there be?

Answer 1

20C5

Answer 2

5 random questions will be chosen from 20. after choosing one, you are left with 19 to choose from, then 18, and it goes on until you are left with 15. So it's 20*19*18*17*16 (or 20!/15!, if you know what this means). this equals to 1860480 combinations