Amarble paperweight shaped similar to a prism weighs 0.2 lb. how much does a similarly shaped marble paperweight weigh if its length, width, and height are tripled?

If we let
l = length
w = width
h = height

The volume of the prism
V = k lwh
where k is the proportionality constant

If we increase the dimensions by three, the new volume will be
9V
Since material is the same, the mass of the larger prism will be 9 times greater than the smaller one.