math
posted by ... .
A cone shaped container with its vertex at the top and its circular base on the ground is filled to 3/4 of its height with water. What fractional part of the container is filled with water?

consider the unfilled part of the cone.
It will be similar to the original cone but its dimension are 1/4 of the large cone
the volumes of similar shapes are proportional to the cube of their corresponding dimensions
So the volume of the smaller unfilled cone is 1/4^3 or 1/64 of the large cone
so if the height is 3/4 filled with water, that would be 63/64 of the volume of the cone