Q. A and B are two taps which can fill a tank individually in 10 minutes and 20 minutes respectively. However, there is a leakage at the bottom which can empty a filled tank in 40 minutes. If the tank is empty initially, how much time will both the taps take to fill the tank (leakage is still there) ? 

1. 10 minutes
2. 5 minutes
3. 7 minutes
4. 8 minutes