Math CentralQuandaries & Queries


Question from dianna, a parent:

This is a 2-fold question. I am getting some mulch that is measured in 1 cubic yard for $25.00.
Walmart has a 2 cubic bag for $3.00. I need to cover a 376 sq ft area. I need to know which is
the best deal and how much I need to buy to cover the 376 sq ft.


Hi Dianna.

1 cubic yard = 1 (yard)3. Since each yard = 3 feet, 1 cubic yard = 1 (3 feet)3 = 27 feet3. So a cubic yard is 27 cubic feet.

The first price is $25 for 27 cubic feet, so that works out to $0.93 per cubic foot.

Walmart's price is $3 for 2 cubic feet, so that works out to $1.50 per cubic foot.

Clearly, by buying in larger quantities you get a better price.

How much to buy depends on the depth you plan. Each inch of depth is 1/12 of a foot, so each inch of depth requires 376/12 = 31.33 cubic feet. Multiply the number of inches by 31.33 to get the number of cubic feet you will need to purchase.

Hope this helps,
Stephen La Rocque.

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