A cistern of capacity 40 litres has an inlet and an outlet pipe. When both the pipes are opened at once, it takes 8 minutes to fill the cistern. However, if the outflow rate is increased 1.5 times, the cistern never gets filled. Which of the following can be the outflow rate? Choose the correct choice from the following answers: A) 8 litres/minute B) 6 litres/minute C) 12 litres/minute D) 9 litres/minute E) 10 litres/minute
DETAILED SOLUTION   Initially, net flow in the tank = 40 litres/ 8 minutes = 5 litres/minute   Now, the increase in outflow should be greater than 5 litres/min for the tank to fill up   Increase in outflow = 1.5x – x = 0.5x   Only in option c) 0.5 X 12 = 6 litres/min &gt; 5 litres/min   12 litres/minuteORRE12 litres/minuteT ANSWER 12 litres/minute
<result>C</result>
A cistern of capacity 40 litres has an inlet and an outlet pipe. When both the pipes are opened at once, it takes 8 minutes to fill the cistern. However, if the outflow rate is increased 1.5 times, the cistern never gets filled. Which of the following can be the outflow rate?