How many rolls of wallpaper each 8 Yards long and 12 inches wide, will paper the sides of a room 13.2 feet by 17.7 feet and 10 feet high, deducting 138 ft^2 for doors and windows?

17

Explanation:

Given parameters:

Dimension of the wallpaper = 8yards and 12 inches

Dimension of the room  = 13.2ft by 17.7ft by 10ft

Area of the windows and doors  = 138ft²

Unknown:

Number of rolls of wallpaper needed  = ?

Solution:

Let us find the surface area of the room first;

  The room is a shape of cuboid;

           Surface area of cuboid  = 2(LW + LH + WH)

       Surface area  = 2(13.2x17.7 + 13.2 x 10 + 17.7 x 10) = 542.64ft²

Area of each wall paper;

  Convert the sides to ft;

              1 yard  = 3 foot

             8 yard  = 8 x 3  = 24ft

Also, 12inches to ft;

       1inch  = 0.083ft

      12inches  = 12 x 0.083  = 0.996ft

Area of each wall paper  = 24 x 0.996  = 23.9ft²

Now, let us remove the area of the windows and doors from that of the room;

   Remaining area = 542.64ft²  - 138ft²  = 404.64ft²

Number of rolls of wallpaper  =   = 17