Question: A tank has two pipes, one fills it in 5 hours and the other empties it in 10 hours. If both are opened together, how long will it take to fill the tank?
Options:
Correct Answer: 4 hours
Solution:
The net rate is 1/5 - 1/10 = 2/10 - 1/10 = 1/10. Therefore, it will take 10 hours to fill the tank.