Multiple choice

If the radius of circle is increased by 4 times,what will be the percentage increase in its area?

  1. 300%

  2. 400%

  3. 1600%

  4. 1500%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Area of a circle = pi r^2. When radius increases 4 times, new area = pi(4r)^2 = 16 pi r^2. The area increases by 16 times, which is a 1500% increase (calculated as (16-1) x 100%). 300% would mean 4 times area, 400% would mean 5 times, and 1600% would mean 17 times the original area. Only 1500% correctly represents a 16-fold increase.

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