a rectangular room is 11ft by 13 ft. the ceiling is 10ft high. a rolll of wallpaper has the dimesion of 2.5ft wide and 50 ft long. how many rolls should you buy

Question

Jonathan wants to wallpaper the four walls of his room. The room is rectangular and measures 11ft by 13ft. The ceiling is 10ft high. A roll of wallpaper Jonathan has chosen is 2.5ft  wide and 50 ft. long. How many rolls should he buy?

 

Answer 1

the perimeter of the room is 2(11 + 13) = 48 ft.

 

Assume we apply wallpaper vertically.

48 / 2.5 = 19.2 This is the number of roll widths required. We must round up to the nearest whole number which is 20.

The height of the walls is 10 ft and each roll is 50 ft long so each roll can paper 5 roll widths. We need 20 roll widths so we need 4 rolls.

 

If we apply horizontally, the 10 foot height is 4 roll widths. The total length to paper is perimeter x 4 = 48 x 4 = 192 feet. 3 rolls is only 150 feet long so we need 4 rolls (there will be 8 feet left over.

 

We can also calculate total area of the walls which is perimeter x 10 = 480 sq. ft

The area of a roll of wallpaper is 2.5 x 50 = 125 sq. ft

 

480 / 125 = 3.84 rolls which rounds up to 4 rolls

The left over is .16 x 125 = 20 sq ft / 2.5 width = 8 feet which is the same leftover amount above.