Christopher is going to install wallpaper on the four walls of his room. Two of the walls are 14 feet long by 9 feet high. The o
ther two walls are 20 feet long by 9 feet high. His options at the wallpaper store are below. One single roll of wallpaper costs $20 and covers 18 square feet of area.
One double roll of wallpaper costs $40 and covers 54 square feet of area.
What is the minimum cost of installing the wallpaper on the four walls of Christopher's room?
2 of the walls are 14 ft by 9 ft.... A = L * W A = 14 * 9 = 126 sq ft.....and since there is 2 of them...2(126) = 252 sq ft
2 of the walls are 20 ft by 9 ft A = L * W A = 20 * 9 A = 180 sq ft....and since there are 2 of them ..2(180) = 360 sq ft
so for all 4 walls, we have : 252 + 360 = 612 sq ft
54 * 11 = 594 sq ft...so we need 11 double rolls...which costs 11(40) = $ 440 18 * 1 = 18 sq ft ....and we need 1 single roll...which costs $ 20
so we have 612 sq ft to cover....11 double rolls cover 594 sq ft and cost 440...and 1 single roll which covers 18 sq ft and cost 20 for a total cost of : $ 460 <==