Practice problem
Solving Optimization Word Problems

You're creating a secret room behind a bookcase for your new mansion. The room is to have a volume of . The width of the base of the room is to be four-fifths the length of the base. Material for the base costs per square foot. Material for the walls costs per square foot. Material for the ceiling costs per square foot. Finally, material for the entrance costs per square foot. Find the minimum cost for constructing this room.
Round your answer to the nearest hundredth.