If the contour interval is 20 meters, which of the following could be a contour value?

If the contour interval is 20 meters, which of the following could be a contour value?

• A. 18 meters
• B. 25 meters
• C. 40 meters
• D. 43 meters

Answer: (C)

Contour lines sit at elevations that advance in fixed steps equal to the contour interval. With a 20-meter interval, the elevations are spaced by 20 meters: 0, 20, 40, 60, and so on (assuming sea level as the reference). The number that could be a contour value must be a multiple of 20 from the reference. Among the options, 40 meters fits this pattern, while 18, 25, and 43 do not. So 40 meters is the correct contour value.

Contour lines sit at elevations that advance in fixed steps equal to the contour interval. With a 20-meter interval, the elevations are spaced by 20 meters: 0, 20, 40, 60, and so on (assuming sea level as the reference). The number that could be a contour value must be a multiple of 20 from the reference. Among the options, 40 meters fits this pattern, while 18, 25, and 43 do not. So 40 meters is the correct contour value.