Question: A tank can be filled by a pipe in 8 hours and emptied by another pipe in 12 hours. If both pipes are opened together, how long will it take to fill the tank?
Options:
Correct Answer: 4 hours
Solution:
The net rate is 1/8 - 1/12 = 3/24 - 2/24 = 1/24. Therefore, it will take 24 hours to fill the tank.