Multiple choice

A cistern usually can be filled by a tap in 10 hrs but due to a leak in the bottom it takes 2 hrs more to fill. If the tank filled find, in how many hours leak will empty it.

  1. 24

  2. 45

  3. 40

  4. 60

  5. None of these

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

Tap fills at 1/10 per hour. With leak, effective fill rate is 1/12 per hour. Leak empties at rate = 1/10 - 1/12 = 1/60 per hour. Time for leak alone to empty full tank = 60 hours.