I'm going to assume that this plate is donut-shaped. Let and . The area of this plate would be
Multiply this amount by $5.50/sq. in. to get the cost.
An aluminum plate is made according to the following dimensions. THe outer radius is 12 inches and the inner radius is 5 insches. Use Pi = 3.14 as an approximate value. (a) Hamy square inches in area is the aluminum plate? (b) If the cost to construct the plate is 5.50 per square inch, what is the construction cost?