2014-10-27 09:00:26

Brett wants to put wallpaper in a room of his house. The room measures 8 feet by 6 feet, and the walls have a height of 10 feet. Brett wants to put wallpaper over all four walls but not over the doorway, which measures 3 feet by 8 feet. If the wallpaper he wants to use only comes in strips that measure 20 square feet, how many strips of wallpaper does Brett need to buy?

(A) 9
(B) 10
(C) 12
(D) 13
(E) 14

The correct answer is D
Explanation: Start by finding out the surface area Brett needs to wallpaper. Two of the walls are 8 by 10, meaning they have an area of 80 feet, and two are 6 by 10, meaning they have an area of 60 feet. Thus, the four walls have a total area of 80 + 80 + 60 + 60, or 280 square feet. However, the doorway will not be covered and measures 24 square feet (3 x 8 = 24). Thus, the total amount of wallpaper Brett needs is 280 - 24, or 256 square feet. Since the wallpaper only comes in strips of 20 square feet, divide 256 by 20 to find the number of strips Brett needs: 256/20 = 12.8.

Since Brett cannot buy .8 strips of wallpaper, he will need to round up and buy 13 strips, making choice D correct.