Math CentralQuandaries & Queries


Question from vanessa:

I am having a small problem being a subcontractor
I'll having trouble calculating how much concrete it will take to pour a 400 square yard sidewalk 5' wide 4" depth can you show me the equation to figure out how many yards of concrete i will need. Can you help me please?
Thank you very much and have a wonderful day.

Hi Vanessa,

Since you know the square yardage of the concrete you only need to multiply by the depth to obtain the volume. You need however to express the depth in yards. There are 36 inches in a yard so 4 inches is 4/36 yards. Thus the volume is

400 × 4/36 = 44.4 cubic yards.

Contractors use the term yards to mean cubic yards so the amount of concrete you need is 44.4 yards.


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