Math CentralQuandaries & Queries


Question from david:

hi how many concrete blocks would i need for an extension 50 ft long ,20 ft wide and 12ft height

Hi David,

The concrete blocks that form one of the walls in my office measure 16 inches by 8 inches so each one covers an area of $16 \times 8 = 128$ square inches.


The 50 foot long by 12 foot high wall you want to construct is $50 \times 12 = 600$ inches by $12 \times 12 = 144$ inches so its area is $600 \times 144$ square inches. Thus the number of blocks you need for this wall is

\[\frac{600 \times 144}{128}.\]

Perform the analogous calculation for the 20 foot walls and total the number of blocks you obtain. You will need to add a few extra as there will be some cutting and wastage at the corners.


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