Math CentralQuandaries & Queries


I need to figure how many yards of concrete to use. I work for an asphalt company, and we are expanding into concrete. Currently we measure everything in sq. ft. So we came up with 6,960 sq ft of concrete to remove and replace. Currently there is 6" of concrete, and 2" of bedding material. We would like to replace only 4.5" of concrete, the rest in bedding. Here is how I figured, am I correct.
6,960 Sq ft (to simplify I made the Sq ft 350 X 20 ) 350 ft X 20 ft X .33 (1/3 ft or 4") = 2,310 cubic feet 2,310 cb ft / 27 = 85.55 cubic yards
Is this correct?

Hi Jeremy,

What you did is correct but the simplification of 4.5 inches to 4 inches makes quite a difference. The thickness is 4.5/12 feet and hence you have

6,960 x 4.5/12 = 2610 cubic feet

which is

2610/27 = 96.7 cubic yards.


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