math is hell

Guys, how the hell are we expected to be able to answer carp like this I don't understand. Example below:

1. A cylindrical water tank with a radius of 5 meters and a height of 10 meters is being filled at a constant rate of 3 cubic meters per minute. How fast is the water level rising when the water is 6 meters deep?

   Like what in cods name? Are our teachers tweaking?