Posted by some kid on .
A conical tank sits point down, at ground level, so that the circular top of the tank is parallel
to the ground. The tank is 5.0 meters tall, and the top of the tank has a diameter of 3.0 meters. The tank is half full of water. What is the water level (depth)?

math 
MathMate,
The volume of similar solids is proportional to the cube of the linear ratios.
For example, a cube of side x has a volume of (1/2)³=1/8 of another cube of side 2x.
Look for (1/?)³=1/2.