PeepalTree wrote:
A circle with a radius of 4 feet is cut from a piece of sheet metal with uniform thickness. The circle weighs 20 pounds. If another circle is cut from the same sheet and weighs 60 pounds, then its radius is closest to which of the following?
A. 6 feet
B. 7 feet
C. 8 feet
D. 9 feet
E. 10 feet
Weight is calculated from the area.
Given, 20 pounds corresponds to an area of \(\pi(4)^2\)
So area of the circle with unit pound(1 pound)=\(\frac{\pi(4)^2}{20}\)
Since the circle with weight 60 pounds is cut from the
same metal sheet we can correlate the unit pounds of the first circle with the second circle.
Hence, area of the circle with 60 pounds=\(\frac{\pi(4)^2}{20}*60\)=\(48\pi\)
So, radius of the circle=\(\sqrt{\frac{48\pi}{\pi}}\)=\(\sqrt{48}\approx{7}\)
Ans. (B)
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Regards,
PKN
Rise above the storm, you will find the sunshine
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60% (01:32) correct 
