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Four concentric circles are drawn with radii of 1, 3, 5 and 7. The inner circle is painted black, the ring around it is white, the next ring is black and the outer ring is white. What is the ratio of the black area to the white area? Express your answer as a common fraction.

 May 9, 2023
edited by Guest  May 9, 2023
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The area of a circle is πr^22, so the areas of the circles are 1, 9, 25, and 49, respectively. The black area is 9 + 25 = 34, so the ratio of black area to white area is 34/16 = 17/8​​.

 May 9, 2023

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