A frustum is formed when a plane parallel to a cone’s base cuts off the upper portion as shown.

A cone is shown. The top of the cone is cut off to form a frustum of the bottom portion. The smaller cone formed has a radius of 1.5 and a height of 6.4. The frustum has a radius of 3 and a height of 6.8.

What is the volume of the frustum? Express the answer in terms of π.

15.6π units3
20.4π units3
34.8π units3
44.4π units3