There are two taps (A and B). A can fill the tank in 12 hrs and B can empty the tank in 20 hrs. If the taps open alternatively for 1 hrs each and A opens the first. In how much time 60% of the tank will be filled.
1
42 hours 24 minutes
2
32 hours 48 minutes
3
18 hours 32 minutes
4
36 hours 24 minutes
5
28 hours 42 minutes