The radius of a circle has been reduced from 9 cm to 7 cm . the appropriate percentage decrease in area is?
Options:
A . 39.5 %
B . 34.5 %
C . 65.5 %
D . 31.5 %
Answer: Option A
Original area = (22/7) x 9 x 9 cm2New area = (22/7) x 7 x 7 cm2? Decrease = 22/7 x [(9)2 -(7)2] cm2=(22/7) x 16 x 2 cm2Decrease percent = [(22/7 x 16 x 2) /( 7/22 x 9 x 9)] x 100 %= 39.5 %
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