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?
Correct option is
Explanatory Answer :
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
in option C, we have , 0.5 * 12 = 6 litres/min > 5 litres/min
Hence, the answer is "12 litres/minute".
so , C is the correct option