Calculus
posted by JEUCD 12/1/11 .
A certain magical substance that is used to make solid magical spheres costs per cubic foot. The power of a magical sphere depends on its surface area, and a magical sphere can be sold for per square foot of surface area. If you are manufacturing such a sphere, what size should you make them to maximize your profit per sphere?
Thank you very much for your help. =)

Does the price depend on the magical power? What is the relations between:
magic power and price
cost / cubic foot
selling price / sq. ft
If the magic power doesn't count, then make the spheres as physically possible.