Multiple choice

Pipe A can fill a tank in 4 hours and pipe B can fill it in 6 hours. If A, B and an outlet which removes 12 litres of water in an hour, are opened together, the tank is filled in 6 hours. The volume of the tank is -

  1. 56 ltr.

  2. 42 ltr.

  3. 51 ltr.

  4. 48 ltr.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe A fills 1/4 tank per hour, Pipe B fills 1/6 tank per hour, outlet removes 12 liters per hour. Together in 6 hours: 6*(1/4+1/6) - 72 = tank capacity. This gives 6*(5/12) - 72 = V, so 2.5V - 72 = V, meaning 1.5V = 72, so V = 48 liters. Let V be tank volume, then (V/4 + V/6 - 12)*6 = V.

Keep practicing — related questions