The Light List indicates that a light has a nominal range of 20 miles and is 52 feet (16 meters) high. If the visibility is 20 miles and your height of eye is 20 feet (6 meters), at what approximate distance will you sight the light?

Correct Answer: Option C — 13.5 nm

Geographic range is 1.17 * sqrt(52) + 1.17 * sqrt(20), which is 8.4 + 5.2 = 13.6 nm. Since the visibility is 20 miles, the geographic range is the limiting factor. The light will be sighted at the geographic range, which is approximately 13.5 nm.