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Answer:
21/2π ≈ 33 square inches
Explanation:
The formula for the area of a circle is ...
A = πr^2
In terms of diameter, this is ...
A = (π/4)d^2 . . . . . . . where r = d/2
Each at 3/8 of the pizza area, so their portion of the circles with diameter d was ...
serving size = (3/8)(π/4)d^2 = (3π/32)d^2
Then the difference in serving sizes, based on the difference in diameters, is ...
(3π/32)(16^2 -12^2) = (3π/32)(112) = 21/2π . . . square inches
Mark at (21/2)π square inches more pizza than Jane.
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That's about 32.99 square inches more.