A container holds the equivalent of 30 glasses of water. If you turn on the tap at the bottom, it takes 10 seconds to fill a glass with water. How long will it take before the container runs dry if the tap is left turned on?

The answer is dependent on the head of water available which would have an effect on the discharge rate as this will diminish as the water level reduces.

Oh if you want to be all scientific then I will say 10 minutes as the water does not run out at a constant rate. The second glass will take longer to fill than the first, because there will be less water in the container, and therefore less pressure on the bottom. Averaging out each glass will take 20 seconds so therefore from full to empty will take 30 x 20 = 600 seconds = 10 minutes.

9 minutes 50 seconds if the first glass has already gone.

SOTHC you are on a mission to prove that your more than just a cheap comedian, aren't you...well congratulations - you are correct!