John is laying the foundation for 3 homes. Each home needs a slab of concrete that is 100 feet by 100 feet by .5 feet. Concrete has a density of 150 pounds per cubic foot. A pound of concrete cost $.02 per pound. How much does the foundation cost?
Thoughts? Step-by-step reasoning:
The volume of the slab is 100 * 100 * .5 = 5000 cubic feet. So it weighs 5000 * 150 = 750000 pounds. That means the cost is 750000 * $0.02 = $15,000 per house. So the total cost for all 3 houses is $15000 * 3 = $45,000.
Thus, the answer is 45000.