Question
The radius of a circle is increased by 20%. Find the
percentage increase in the area of the circle.Solution
The area of a circle is A = ΟrΒ². If the radius increases by 20%,Β the new radius is 1.2r. The new area is A' = Ο(1.2r)Β²Β = 1.44ΟrΒ². The percentage increase in area = (1.44 - 1) Γ 100 = 44%. Correct answer: c) 44%
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