Tip
Ratio and proportion problems, any problems that involve percents, and word problems that test rates may be tested.
Sample Problem
Machine A and Machine B work at constant rates to produce billing envelopes. To produce 20 billing envelopes, it takes Machine A 4 minutes and Machine B 5 minutes. At these rates, what is the total number of envelopes that Machine A and Machine B can produce in 40 minutes?
Answer Options
(A) 90
(B) 180
(C) 360
(D) 380
(E) 400
View Correct Answer
(C) 360
Since Machine A produces 20 billing envelopes in 4 minutes, it will produce 200 billing envelopes in 40 minutes. Since Machine B produces 20 billing envelopes in 5 minutes, it will produce 160 billing envelopes in 40 minutes. 200 + 160 = 360
