Three taps A, B and C can individually fill an empty tank in 6, 18, 24 hrs respectively. A tap D can empty the full tank in 8 hrs. All four taps A, B, C, and D are opened at 5 am, 6 am, 7 am and 8 am respectively. At what time will the tank be full?
1
10 : 30 am
2
11 : 40 am
3
12 : 40 pm
4
12 : 42 pm