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?

Density is a property of a material which describes the mass of a material per unit volume. We calculate as follows:

Density = mass / volume

mass = 12000 lbs

volume = lwh = (2.5) (2.5) (12) = 75 ft^3

Density = 12000 / 75 = 160 lbs/ft^3

160 pound per cubic foot