You need to manufacture a cylindrical pot, without a top,

with a volume of 1 ft3. The cylindrical part of the pot is to be made of aluminum, the bottom of copper. Copper is five times as expensive as aluminum. What dimensions would minimize the total cost of the pot?

I Know how to do optimization. Find the derivative, set it equal to zero, find the absolute max and min, and compare it to the intervals given. But this problem is really bothering me. Can anyone help? what are the intervals here? and how do you set up the geometry/sketch of this?