Question: A tank is filled by two pipes in 18 hours and 24 hours respectively. If both pipes are opened together, how long will it take to fill the tank?
Options:
Correct Answer: 12 hours
Solution:
The combined rate is 1/18 + 1/24 = 4/72 + 3/72 = 7/72. Therefore, it will take 72/7 hours or approximately 10.29 hours.