There are 3 tapes in a tank, 2 for filling water and 1 for drain. The first 2 tapes can fill the tan

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08 Jul 2011 tape and tank

There are 3 tapes in a tank, 2 for filling water and 1 for drain. The first 2 tapes can fill the tank alone in 10 and 12 hours respectively, whereas 8 hours are required to drain all the water by third tape alone.
If we open all the 3 tapes, then hours required to fill the tank completely are

OPtion

1) 6
2) 100/9
3) 7
4) 13/2
5) 5
6) 120/7
7) 92/5
8) 100/13
9) 130/9
10) none of these

Solution

total tank filled in 1 hour = (1/10)+(1/12)-(1/8) = 7/120
so hours required to fill the complete tank = 120/7

Correct Option: 6 Best Solution (0)