If the radius of a circle is decreased by 50% , find the percentage decrease in

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Question
If the radius of a circle is decreased by 50% , find the percentage decrease in its area.
Options
A. 75%
B. 65%
C. 35%
D. 25%

Correct Answer

75%

Explanation

let original radius = r and new radius = (50/100) r = r/2

original area = ${?r}^{2}$ and new area = $? {(r / 2)}^{2}$

decrease in area = $3 {?r}^{2} / 4$ * $\frac{1}{{?r}^{2}}$ *100 = 75%

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