What is the cost per square inch?

A 9 inch apple pie sells for $6.  What is the cost per square inch rounded to the nearest cent?

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Find the area of the apple pie.  Then, divide the cost by the area to find the cost per square inch.

The radius (halfway across) of the apple pie is 4.5 inches {half of 9}.
Area of a circle = πr² 
=  3.14(4.5²)  {substituted 3.14 for π and 4.5 for r}
≈ 3.14(20.25)  {squared the 4.5}
≈ 63.585  {multiplied, approximately because π is rounded to 3.14}

The area of the pie is approximately 63.585 in².

Divide the cost by the area to find the cost per square inch.

6 ÷ 63.585  {divided the cost by the area}
≈ 0.09  {divided} 

The cost per square inch is approximately $0.09.

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