An inlet pipe can fill a tank in 7 hours, and a drain pipe can empty the same tank in 9 hours. If the drain is left open while filling the tank, it would take 16 hours to fill the tank.

Question

Quizplus · Accepted Answer

If the drain is left open while filling the tank, it will empty the tank while it is being filled. Therefore, the time taken to fill the tank would be longer than 16 hours. One way to solve the problem is by using the formula:

work done = rate x time

Let's assume that the capacity of the tank is 1 unit (it could be any unit of measurement, such as liters or gallons). Then, the inlet pipe can fill the tank at a rate of 1/7 units per hour, and the drain pipe can empty the tank at a rate of 1/9 units per hour. If both pipes are open, they are working against each other and the net rate of filling is:

1/7 - 1/9 = 2/63 units per hour

This means that it takes 63/2 hours (31.5 hours) to fill the tank with the drain open. Therefore, the statement is false.

An Inlet Pipe Can Fill a Tank in 7 Hours