A layer of dirt must be spread over a circular area 13.5 feet in diameter. How deep a layer will be obtained using 75 cubic feet of dirt? Round to the nearest tenth. Solution Dirt deposit would form a cylider of 75 cubic feet of volume Volume = pi(r^2)*h r = 13.5 feet 75 = pi(13.5)^2 *h where h is depth of dirt h =0.13 = 0.1 feet.