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 in feet?

• A. 0.5 ft
• B. 0.667 ft
• C. 0.333 ft
• D. 1.0 ft

Answer: (B)

To determine the elevation at the bottom of the 4-inch concrete slab, you need to convert the thickness of the slab from inches to feet. Since there are 12 inches in a foot, 4 inches is equivalent to 4/12 feet, which simplifies to 1/3 feet or approximately 0.333 feet.

Given the top of the slab is at one foot above the benchmark, you can find the elevation of the bottom by subtracting the thickness of the slab from the elevation of the top. This can be expressed as:

1.0 ft (elevation at the top) - 0.333 ft (thickness of the slab) = approximately 0.667 ft.

Thus, the correct answer reflects the elevation at the bottom of the slab as 0.667 feet above the benchmark. This answer takes into account the proper conversion and simple arithmetic involved in finding the elevation difference.