Question

As a technical engineer, you must calculate the elevation of a Point marked on a topographic map. The distance between the 420-foot and 440-foot contour lines is 0.5 inches, and the marked point between them is 0.2 inches from the 420-foot contour. What is the elevation, in feet, of the marked point?​

A.100
B.424
C.428
D.430
E432

Answer 1

The correct answer is C, 428 feet.

To calculate the elevation of the marked point, we need to interpolate between the two contour lines. The difference in elevation between the two contour lines is 20 feet (440 - 420 = 20). And since the distance between the two contour lines is 0.5 inches, each 0.1 inch increment represents a 4-foot change in elevation (20 feet ÷ 0.5 inches = 40 feet per inch ÷ 10 = 4 feet per 0.1 inch).

Since the marked point is 0.2 inches from the 420-foot contour, the elevation of the marked point can be calculated by adding 8 feet (4 feet x 0.2 inches) to the 420-foot contour line: 420 + 8 = 428 feet.