A pipe can empty the tank in 8 hours and another fill 6 litres in 1 min. If both pipe opened, the tank is emptied in 12 hours. The capacity of tank is ?	Select:
A) 8000
B) 8240
C) 8440
D) 8640
E) 8840
Let Capacity of the Tank is 100%.   First Pipe can empty the tank in = 8 hours = 8 * 60= 
<gadget id="calculator">8 * 60</gadget>
<output>480</output>
480 min   Work rate of the pipe= X/480 litre per min.   The work rate of both pipe = X/(12*60) litre per min =   (X/480) - (X/720 )= Work rate of Second pipe   720X - 480X = 6 litere * 720 *480   240X = 6*720*480   X = 8640 litres   ANSWER :OPTION 8640
<result>D</result>
A pipe can empty the tank in 8 hours and another fill 6 litres in 1 min. If both pipe opened, the tank is emptied in 12 hours. The capacity of tank is ?