The amount of material needed to cover a ball varies directly with the square of the radius. It takes about 221.63 cm2 of material to cover a ball with a radius of 4.2 cm. What is the radius of a ball that needs 352.92 cm2 of material to cover it?
1 Answer
Sep 29, 2016
Explanation:
Since the amount of material necessary to cover the ball varies directly with the square of the radius, we know
Or:
Now we want to find
We could solve for k and then plug in, but a simpler method would be to divide our equations and solve for
Notice how the k's cancel out, and we can solve for