Question 1197332
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Inside radius is  r = 10.20/2 = 5.10 meters.


Outside radius is R =  5.10 m + 0.5 m = 5.6 m.


Cross-sectional area is  {{{pi*R^2 - pi*r^2}}} = {{{3.14*5.6^2 - 3.14*5.1^2}}} = 16.7 m^2.    <U>ANSWER</U>
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Solved.