The volume of a cone is equal to
Volume = pi * r^2 * h / 3
The volume of a cylinder is equal to
Volume = pi * r^2 * h
The cone is filled with 6 cubic inches colored sand.
As you observed, the volume of the cone is 1 / 3 of the volume of the cylinder.
Cone = Cylinder / 3
6 = Cylinder / 3
Cylinder = 18
So the answer is A. 18.
