# Math Help - Inverse Variation

1. ## Inverse Variation

This problem was easily solved : ((4000^2)x200) / (5000^2)=128
Notes:
Original Problem ( simplified ) : The weight of a man is 200 pounds 4000 miles ( surface ) from the center of the earth, how much does he weigh 1000 miles above the surface.

2. ## re: Inverse Variation

Originally Posted by exerpt
The Weight of a body varies inversely as the square of its distance from the center of the earth. If the radius of the Earth is 4000 miles long, how much would a 200lb. man weigh 1000 miles above the surface?
the statement above translated into an equation ...

$W = \frac{k}{d^2}$

where W = weight, d = distance, and k = the constant of proportionality

use your Earth surface info ( W = 200 , d = 4000) to solve for k, then determine W at d = 4200

3. ## re: Inverse Variation

Thanks for the quick reply, helps quite a bit