Arithmetichard · Past Paper

If the radius of a circle is increased by 50%, find the percentage increase in its area.

A50%
B100%
C125%
D150%

✓ Correct Answer: C125%

Area depends on r^2. New area = (1.5r)^2 = 2.25r^2. Increase is 2.25 - 1 = 1.25 = 125%.

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