Question

A water tank can be filled by an inlet pipe in 8 hours. It takes twice that long for the outlet pipe to empty the tank. How long will it take to fill the tank if both pipes are open?

Answer 1

If both pipes are open, it fills the tank in `16` hours .

Explanation:

Inlet pipe fills water tank in `8` hours.

Outlet pipe empties the tank in `8xx2=16` hours,

therefore, outlet pipe empties half the tank in `8` hours, while inlet pipe has filled the tank in same `8` hours.

therefore, if both pipes are open in `8` hours it fills only half the tank.

Hence, if both pipes are open, it fills the tank in `8xx2=16` hours .