Question

If S is the set of positive integers that are multiples of 7, and if T is the set of positive integers that are multiple of 13, how many integers are in the intersection of S and T?
(A) None

(B) One

(C) Seven

(D) Thirteen

(E) More than thirteen

Answer 1

Answer:

Option E

Explanation:

If We take the intersection of S and T, 91 elements will be in it i.e. 91 (Because If we multiply 7 and 13 we get 91)

Answer 2

Answer:

E. More than thirteen

Explanation:

S is the set of multiples of 7, meaning 7, 14, 21, 28 and so on to infinity

T is the same but with 13 instead

Both sets are infinite.

The first intersection would be 7x13 (91)

Though it would be difficult to find 14 of them to prove it, we don't have to since we know both sets are infinite and will eventually have intersections the higher they go