Two cones are the same size w/ radius 3in and height 6in. One has a density of 80oz/in^3 at its base and 50oz/in^3 at the vertex. The other has a density of 50oz/in^3 at its base and 80oz/in^3 at its vertex. In both cones, the density varies linearly with the distance from the plane of the base. What are the masses of the cones? How do you solve this? The answers are supposed to be 1350pi and 1035pi, but I cannot get the right answer. One time I got 337.5pi which is 1/4 of 1350pi, but can't see why I would need to multiply by four. Thanks!