A marble pillar in the shape of a square prism has a length and width of 2.5 feet and a height of 12 feet. The pillar weighs 12,000 pounds. How many pounds per cubic foot is the density of the marble?
The volume of the prism is 2.5 * 2.5 * 12 = 75 ft^3
The density = mass / volume = 12000 lb / 75 ft^3 = 160 lb / ft^3