Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: a pump can fill a tank with a water in 2 hours . because of a leak , it took 3 hours to fill the tank . the leak can drain all the water of the full tank in how many hours ?
6
1.5 hours.