Commercial Contractor Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

To find the elevation at the lowest perimeter point, you start with the highest point, which is given as 87.2 feet, and calculate the total slope over the distance of the paved area.

The slope of 1/8 inch per foot means that for every foot in horizontal distance, the elevation drops by 1/8 inch. First, it is necessary to convert this slope into feet for easier calculations. Since there are 12 inches in a foot, 1/8 inch converts to 1/8 ÷ 12 = 1/96 feet.

Next, you need to calculate the total horizontal distance of the paved area. Since the area is 140 feet wide and presumably slopes towards the lower perimeter, you would use this width to calculate the total drop in elevation across that width.

The drop in elevation over a distance of 140 feet can be calculated by multiplying the slope per foot by the length:

Total drop = 140 feet × (1/96 feet per foot) = 140/96 feet = 1.4583 feet.

Now, subtract this total drop from the highest elevation:

Lowest elevation = 87.2 feet - 1.4583 feet ≈ 85.7417 feet