Question

A storage shed is to be built in the shape of a (closed) box with a square base. It is to have a volume of 150 cubic feet. The concrete for the base costs $4 per square foot, the material for the roof costs $2 per square foot, and the material for the sides costs $2.50 per square foot. Express the cost of the material as a function of the (length of the) side of the base.

Answer 1

Answer:

$C(s) = 6s^2 + \dfrac{1500}{s}\\\text{where s is the side of base.}$

Step-by-step explanation:

We are given the following in the question:

A storage shed is to be built in the shape of a (closed) box with a square base.

Volume = 150 cubic feet

Let s be the edge of square base and h be the height.

Volume of cuboid =

$l\times b\times h$

where l is the length, b is the base and h is the height.

Volume of box =

$s^2h = 150\\\\h = \dfrac{150}{s^2}$

Area of base =

$\text{side}\times \text{side} = s^2$

Cost of concrete for the base = $4

Cost of base($) = $4s^2$

Area of roof =

$\text{side}\times \text{side} = s^2$

Cost of material for the roof = $2

Cost of roof ($) = $2s^2$

Area of 4 walls =

$4\times (sh)\\=4sh$

Cost of material for the side = $2.50

Cost of material of side($) =

$2.50\times 4s(\dfrac{150}{s^2})\\\\=\dfrac{1500}{s}$

Total cost

= Cost of base + Cost of 4 sides + Cost of roof

$C(s) = 4s^2 + \dfrac{1500}{s} + 2s^2\\\\C(s) = 6s^2 + \dfrac{1500}{s}$

is the required cost function.