Question 1058156
The volume of the frustum is:


{{{V = (1/3)(a^2 + ab + b^2)h}}}


where a and b are the lengths of the sides of the square bases, and h is the altitude.


For this particular frustum, the volume is:


V = 1/3(4^2 + 4(7.5) + (7.5)^2)(61) = 2,079.08 cubic feet


With a density of 170 lb. per cubic foot, the total weight is:


(2,079.08 cu. ft.)(170 lb / cu. ft.) = 353,443.6 lb