Which set is finite? A the set of all factors of 20
B. the set of all multiples of 20
C. the set of all integers less than 20
D. the set of all integers greater than 20
E. the set of all fractions less than 20.

Choice A) The set of all factors of 20

Explanation:

Let's go through the answer choices

A) The factors of 20 are 1,2,4,5,10,20. This list does not go on forever, so this set is finite.B) The multiples of 20 are 20,40,60,80,100,... and this list does go on forever. Simply add 20 to the last value to get the next one. This set is not finite, so it is infinite.C) This set is infinite as well because there are infinitely many negative integers. Any negative number is smaller than a positive number.D) There are infinitely many integers, so there are infinitely many integers greater than 20. This set is infinite.E) It's the same idea as before. This set is infinite. There are infinitely many rational numbers smaller than 20.