Question

david built a large wooden storage box. the box was in the shape of a rectangular prism, as shown below. he covered all the sides of the box with special wallpaper that cost a total of $324. how much did the wallpaper cost per square foot?

Explanation:

Step1: Calculate surface - area of the rectangular prism

The surface - area formula of a rectangular prism is $SA = 2(lw+lh + wh)$, where $l = 6$ ft, $w = 3$ ft, and $h = 4$ ft.
$SA=2(6\times3 + 6\times4+3\times4)$
$=2(18 + 24+12)$
$=2\times54$
$ = 108$ square feet.

Step2: Calculate cost per square - foot

The total cost of wallpaper is $\$324$. To find the cost per square - foot, divide the total cost by the surface - area.
Cost per square - foot $=\frac{324}{108}=3$.

Answer:

$3$