A tank is normally filled in 4 hours. But it takes 5 hours to fill, when there is a leak at the bottom of the tank.
If the tank is full, in how many hours can it be emptied by the leak?
1
12
2
20
3
10
4
15
A tank is normally filled in 4 hours. But it takes 5 hours to fill, when there is a leak at the bottom of the tank.
If the tank is full, in how many hours can it be emptied by the leak?