The pyramid's formula for Volume is identical to the formula for Volume of a prism, except for having a factor 1/3.
Base Area and height being the same for a pyramid and a prism, the volume of the pyramid is always one third that of the prism.
A similiar fact pertains to Cone vs Cylinder...these 3 dimensional volumes have a ratio of 1/3 to one another.
In two dimensions, there's a ratio of 1/2 between areas of triangles and rectangles having the same base & height.
