9514 1404 393
Answer:
244 tiles
Step-by-step explanation:
These "border" problems can be a little tricky.
The tiles are 1 ft square, so an integer number of them fit along each of the sides. The 40-ft side will take 40 tiles for its border, and the 80-ft side will take 80 tiles.
The total number of tiles along each of the four sides is ...
40 + 80 + 40 + 80 = 240 . . . tiles
However, there is also a tile in each of the corners. There are 4 of those, so the total number of tiles surrounding the pool is ...
240 +4 = 244 tiles
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<em>Alternate solution</em>
For a border of width w, the outside area of the pool plus the border is ...
A = LW = (80 +2w)(40 +2w) = 80·40 +240w +4w²
The area of the pool is ...
A = LW = (80)(40) = 80·40
Subtracting the area of the pool from the total area including the border gives ...
border area = (80·40 +240w +4w²) -(80·40) = 240w +4w²
We know the width of the border is 1 foot, so w=1 and the border area is ...
border area = 240·1 +4·1² = 244 . . . . square feet
Each tile is 1 square foot, so 244 tiles are needed for the border.
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It can help to draw yourself a diagram. It can also help to make a small model using blocks, Scrabble tiles, Legos, jigsaw puzzle pieces, squares cut from paper, or even coins (pennies). Anything that will give you an idea of how to count the tiles required to make a border can be helpful.
