Mechanics Practice Exam

To determine the thickness of the walls given a platform height of 7 feet and an inside wall clearance of 6 feet 8 inches, it's essential to understand the relationship between these measurements. First, convert all measurements to the same unit for clarity. The platform height is 7 feet (or 84 inches), and the inside wall clearance is 6 feet 8 inches (or 80 inches). The difference between the platform height and the inside wall clearance will yield the total thickness of the walls. By subtracting the inside wall clearance from the platform height: 84 inches (platform height) - 80 inches (inside wall clearance) = 4 inches. This result indicates that the total thickness of the walls is 4 inches. Thus, the wall thickness that allows for the height difference while maintaining the desired clearance is indeed 4 inches, making that the correct answer.