Help with a math problem: Geography related?

Question

"If the lookout at the top of the ship's mask is 100 feet above water level, and the ship is 15 miles from the shore, is it possible to see someone on shore? What if the ship were 10 miles from shore. Show calculations."

I'm not sure, but a possible equation could be:

k=4/3 times the square root of h

k=distance we can see in miles and h=height of an object above sea level.

Answer 1

The formula for the distance to the horizon is:

k = square root( 2 x Radius of Earth x Height of Mast)

Remember to put all the distances in the same units.

Answer 2

k = sqrt[2h]

where k is in miles and h in feet.

If h=100'

k = 14.1 miles.

So a person at 15 miles cannot be seen, but someone at 10 miles can be seen.