At sea, the distance D to the horizon is directly proportional to the square root of the elevation E of the observer. If a person who is 36 feet above the water can see 7.4 miles, find how far a person 49 feet above the water can see.

The problem says that the distance D to the horizon is directly proportional to the square root of the elevation E of the observer, so:

The person who is 36 feet above the water ⇒ √36=6

A person 49 feet above the water ⇒ √49=7

So, by proportions, you have:

(7/6) x7.4 = 8.63 miles

Therefore, the answer is: a person 49 feet above the water can see 8.63 miles