Wallpaper the four walls of her room

Question

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

Answer 1

Start with finding how much area she wants to cover. The bottom rectangle(the floor) is 11 ft by 13 ft. There is 10 ft of space between the ceiling and the floor.

The height will be your length for each wall and the bottom dimensions (11 and 13) will be your width.

 

The dimensions of each wall, then, are (2)11x10 and (2)13x10

The formula for a rectangles area is length * width and with 2 walls with the same dimension you will have 2 walls that will have the same area. Here's how the equation would look: 

2(11*10)+2(13*10)=480 ft2 (This adds the area of all the walls to get the total amount of space to cover)

Next, find the area of one roll of wall paper. Use the area of a rectangle formula to get this equation:

 

2.5*50=125 ft²

 

Now you can find how many rolls of wall paper she'll need by dividing 125(roll's area) into 480(walls' area) to get 3.84. 

 

Round up so that she'll have enough cover all of the walls completely to get 4 rolls of wall paper needed.