A container is normally filled in 5 hours. However, it takes 6 hours when there is a leak at the bottom. If the container is full, in what time would the leak empty it, if no water is allowed into the container during that period?

30 h

A+ = 5 hrs, A+B- = 6 hrs,

⇒ A + B = 5,

⇒ 6 + B = 5,

⇒ B = -1,

⇒ Time required by outlet B to empty the full tank = \(\frac{30}{1}\) = 30 hrs.