Air flows through a heating duct with a square cross-section with 9-inch sides at a speed of 4.7 ft/s. Just before reaching an outlet in the floor of a room, the duct widens to assume a square cross-section with sides equal to 13 inches. Compute the speed of the air flowing into the room (in ft/s), assuming that we can treat the air as an incompressible fluid. ft/s