<em>Study the Problem</em>
What is the cost of the wallpaper (in dollars per square foot)?
<em>Organize the Facts</em>
The wallpaper covers a rectangle 42 ft by 25.5 ft. It costs $771.12 for that area.
<em>Make a Plan</em>
To find dollars per square foot, we need to divide the dollar amount by the area in square feet. The area needs to be computed. It is the area of a rectangle, so can be found by multiplying length and width.
Plan: multiply length and width of the wall to find its area; divide the cost by that area to find dollars per square foot.
<em>Execute the Plan</em>
area = (42 ft)×(25.5 ft) = 1071 ft²
cost/area = $771.12/(1071 ft²) = $0.72/ft²
<em>Examine the Results</em>
The area is on the order of 40×25 = 1000 ft², and the cost is less than $1000, so the cost will be less than $1 per square foot. The answer is in the right ballpark. If we multiply it out, we should get the given cost:
... 0.72×42×25.5 = 771.12 . . . . agrees with given cost.
The cost of the wallpaper is $0.72 per square foot.
