Multiple choice

Pipes A and B can fill a tank in 10 and 40 hours respectively. If both pipes are opened then, how much time (in hours) it will take to fill the tank?

  1. 9

  2. 6

  3. 7

  4. 8

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipes A and B together fill 1/10 + 1/40 = 5/40 = 1/8 of the tank per hour. Therefore, they will take 8 hours to fill the tank completely. This is a standard pipes and cisterns problem where rates add up when working together.