Question

A machine can insert letters in envelopes at the rate of 120 per minute. Another machine can stamp the envelopes at the rate of 3 per second. How many such stamping machines are needed to keep up with 18 inserting machines of this kind?

(A) 12
(B) 16
(C) 20
(D) 22
(E) 24

Answer 1

I think the answer is D

Hope it helps :-D