SOLUTION: A tank takes 10 hours to fill through a inlet pipe. It takes three times as long to empty through an outlet pipe. How long would it take to fill if both pipes are open? The size i

It's not a trick question and it can be solved.

Inlet pipe takes 10 hours to fill tank.

So in one hour, it fills 1/10 of the tank

Outlet pipe takes 3 times as long i.e. 3* 10 = 30 hours to empty tank.

So in one hour, it empties 1/30 of the tank

If both are open, in one hour

1/10 of the tank is filled and 1/30 is emptied.

So volume of water remaining in tank = 1/10 - 1/30 = 2/30 = 1/15 of the tank.

That is, if both the inlet and outlet are open, 1/15 of the tank gets filled

every hour.

So time taken to fill the whole tank = 15 hours!



Hope you got it :)