aikido_fudoshin wrote:

The number of miles a person can see to the horizon from a point above the surface of the earth is 0.85 of the square root of the persons distance above the surface. Jack is 85 feet higher and sees 4.25 miles farther than Jill. How high are Jack and Jill above the surface?

Let x and y be the distance of Jack and Jill above the earth's surface respectively.

we have: 0.85sqrt x - 0.85sqrt y= 4.25 miles= 26,400 feet

x-y= 85

solve these two equations to get x and y.

Btw, I remember from physics lesson that people's sight (unblocked by obstacle like buildings,etc...) is infinite