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 :)



 

RELATED QUESTIONS

A large water tank has two inlet pipes of different sizes, and one outlet pipe. With the... (answered by josmiceli)

Hi 

The problem:

A large water tank has two inlet pipes of different sizes and one... (answered by nerdybill)

A water tank can be filled by an inlet in 8 hours. It takes twice the long for the outlet  (answered by josgarithmetic)

A water tank can be filled by an inlet pipe in 8 hours. It takes 3 times as long for the... (answered by josmiceli)

A water tank can be filled by an inlet pipe in 6 hours. It takes 3 times as long for the... (answered by richwmiller)

A water tank can be filled by an inlet pipe in 9 hours. It takes 4 times as long for the... (answered by ptaylor)

A water tank can be filled by an inlet pipe in 6 hours. It takes 4 times as long for the... (answered by josgarithmetic)

A water tank can be filled by an inlet pipe in 8 hours. It takes 2 times as long for the... (answered by josmiceli)

A water tank can be filled by an inlet pipe in  
9
  hours. It takes  
4
  times as... (answered by josgarithmetic,ikleyn,greenestamps,math_tutor2020)