Question

A 1.1 m square tank was 60% full of water. Water was added into the tank at the rate of 4 litres per minute. At the same time, water began to leak from a crack at the base of the tank at the rate of 550 cm' per minute. How long did it take to fill the tank completely? Give your answer to the nearest hours and minutes.

Answer 1

net inflow: 4 - 0.55 = 3.45 L/min
I assume a "1.1m square" tank is a cube of 1.1 m on a side. Since it is 60% full, that means it still needs 0.4 * 1.1^3 = 0.5324 m^3 = 532.4 L of water to be full.
532.4L / (3.45 L/min) = 154.3 minutes to fill