Math CentralQuandaries & Queries


Question from Chris, a parent:

I need to know how many sheets of 4 foot by 8 foot by 1 inch foam I will need to cover the bottom of a 27 foot diameter pool? Thanks!

Hi Chris,

First find the area of the bottom of the pool (a circle) and the area of each sheet of foam (a rectangle).

Area of a Circle = π × radius2 = π × (diameter/2)2 = π × diameter2/4 = 3.14 × (27ft)2/4 = 572.265 ft2

Area of rectangle = length × width = 4 ft × 8 ft = 32 ft2

By dividing the area of the bottom of the pool by the area of one sheet of foam, it will let us know how many times bigger the bottom of the pool is than one sheet.

Area of bottom of the pool / area of sheet of foam = 572.265 ft2 / 32 ft2 = 17.88

Since the number sheets must be a whole number, 18 sheets of foam will be needed to cover the bottom of the pool.

There will undoubtedly be some wastage when you cut the sheets so it is possible you will need 19 sheets.


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