The ratio between the volume of the small cone to that of the frustum is 1:1.
Notice that the bigger cone is double than the smaller cone, which means the smaller cone is half of the volume of the bigger cone, if you wipe the small one, you would have the frustum with the same volume as the wiped part, because if you delete the smaller cone, you would be deleting half volume of the bigger cone, giving at the end a relation 1 : 1 between the frustum and the smaller cone.
