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
