Question 22878
SEE THE FOLLOWING EXAMPLE AND TRY.IF YOU HAVE DIFFICULTY ,I SHALL WORK OUT FOR YOU.KEY IS TO FIND HOW MUCH WILL BE FILLED OR DRAINED IN 1 HOUR BY EACH PIPE AND THEN ESTIMATR FOR THE COMBINATION IN 1 HOUR AND THEN TAKE RECIPROCAL TO FIND THE HOURS NEEDED TO FILL OR EMPTY THE FULL TANK OR WHATEVER IS NEEDED 
Mixture_Word_Problems/18599: Need help with this, The inlet pipe of an oil tank can fill the tank in 1 hour, 30 minutes. The outlet pipe can empty the tank in 1 hour. How long does it take to empty the tank if both pipes are open?1 solutions Answer 9051 by venugopalramana(345) on 2005-11-08 02:05:51 (Show Source): The inlet pipe of an oil tank can fill the tank in 1 hour, 30 minutes. The outlet pipe can empty the tank in 1 hour. How long does it take to empty the tank if both pipes are open?inlet pipe fills 1 tank in 1hr 30 mts =1.5=3/2 hrs.or inlet pipe fills ...1/(3/2)=2/3 tank in 1 hr.out let pipe empties 1 tank in 1 hr....so assuming the tank is full at the start water to be emptied =1 tank and in 1 hr inlet fills 2/3 tank and out let empties 1 tank ..so net out flow is 1-2/3=(3-2)/3=1/3 tank in 1 hour.so 1/3 tank emptying needs .....1 hrthen 1 tank emptying needs ......? hrs...= 1*1/(1/3)=3 hrs.