If the top of a 4-inch concrete slab is at one foot above the benchmark, what is the elevation at the bottom of the slab?

To determine the elevation at the bottom of a 4-inch concrete slab when the top of the slab is at one foot above the benchmark, it's essential to convert the thickness of the slab from inches to feet. Four inches is equivalent to one-third of a foot (4 inches ÷ 12 inches per foot = 0.333 feet).

Given that the top of the slab is at one foot, you subtract the thickness of the slab from this elevation to find the elevation at the bottom. Therefore, you would calculate:

1 foot (the elevation at the top of the slab) - 0.333 feet (the thickness of the slab) = 0.667 feet.

This calculation correctly matches the answer indicating that the elevation at the bottom of the slab is 0.667 feet. This demonstrates a fundamental understanding of property elevation, as well as the impact of concrete slab thickness on overall elevation measurements.