An outlet pipe empties a tank which is full in 8 hours. If the inlet pipe is kept open, which lets water in at the rate of 8 litres/min then outlet pipe would take 4 hours longer. Find the capacity of the tank. Select the correct option.
A) 8600 litres
B) 200 litres
C) 12800 litres
D) 11520 litres
E) 13200 litres
Let the rate of outlet pipe be x liters/hour;   Rate of inlet pipe is 8 litres/min, or  8*60= 
<gadget id="calculator"> 8*60</gadget>
<output>480</output>
480 liters/hour;   Net outflow rate when both pipes operate would be x-480 liters/hour.   Capacity of the tank= x*8 hours = (x-480)*(8+4) hours   8x=(x-480)*12 --&gt; x=1440 --&gt; capacity = 8x = 11520 liters.   Answer: 11520 litres.
<result>D</result>
An outlet pipe empties a tank which is full in 8 hours. If the inlet pipe is kept open, which lets water in at the rate of 8 litres/min then outlet pipe would take 4 hours longer. Find the capacity of the tank.