Atank can be filled by one pipe in four hours and by a second pipe in six hours; and when it is full, the tank can be drained by a third pipe in three hours. if the tank is empty and all three pipes are open, in how many hours will the tank be filled?

8 hours
12 hours
24 hours

12 hours

Step-by-step explanation:

Let t be time to fill with all pipes open

All the pipes will complete a single job that is = 1

Given is that the tank can be filled by one pipe in 4 hours and by a second pipe in 6 hours and can be drained by a third pipe in 3 hours.

So, equation forms;

=>

=>

And t = 12 hours

Hence, it will take 12 hours to do the job.

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step-by-step explanation: