Question

Alina wants to make keepsake boxes for her two best friends. She doesn't have a lot of money, so she wants to make each box described so that it holds as much as possible with a limited amount of material.

For Jen, Alina wants to make a box with a square base whose sides and base are made of wood and whose top is made of metal. The wood she wants to use costs 5 cents per square inch, while the material for the metal top costs 12 cents per square inch. What is the largest possible box (in terms of volume measured in cubic inches) that Alina can make for Jen if she only has $30.00 to spend on materials? (Round your answer to three decimal places.)

Answer 1

So Alina can make a box with dimensions 8.445 inches by 8.445 inches by 8.445 inches (with a metal top) that will hold approximately 606.526 cubic inches.

Explanation:

Let's assume that the length of one side of the square base of the box is "x". Then the height of the box is also "x" to maximize the volume.

The surface area of the box (excluding the top) is given by:

2(x^2) + 4(x^2) = 6(x^2)

The surface area of the metal top is:

x^2

The total surface area of the box is the sum of the surface area of the box and the surface area of the metal top:

6(x^2) + x^2 = 7(x^2)

The cost of the wood for the box is:

5 cents per square inch * 6(x^2) = 30x^2 cents

The cost of the metal for the top is:

12 cents per square inch * x^2 = 12x^2 cents

The total cost of the box is:

30x^2 + 12x^2 = 42x^2 cents

We want to find the maximum volume of the box that can be made with $30, which is 3000 cents. Therefore, we can set up the equation:

42x^2 = 3000

Solving for x, we get:

x^2 = 71.429

x ≈ 8.445

Therefore, the maximum volume of the box is:

V = x^2 * x = (8.445)^3 ≈ 606.526 cubic inches.

So Alina can make a box with dimensions 8.445 inches by 8.445 inches by 8.445 inches (with a metal top) that will hold approximately 606.526 cubic inches.