Multiple choice

If the radius of a circle is increased by 20%, its area is increased by (a) 44% (b) 20% (c) 79% (d) None of these

  1. A

  2. B

  3. C

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

Area of a circle is proportional to the square of the radius. If the radius increases by 20%, the new radius is 1.2r. The new area is pi * (1.2r)^2 = 1.44 * pi * r^2, which is a 44% increase.

AI explanation

When a single dimension of a 2D figure is increased by 20%, the successive percentage increase formula is x + y + (xy / 100) to account for the squared relationship in area. Applying the values gives 20 + 20 + (400 / 100), which equals 44. The area is increased by 44%.

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