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  • If the radius of a circle is diminished by 10%, then its ...
Multiple choice general knowledge math & puzzles

If the radius of a circle is diminished by 10%, then its area is diminished by:

  1. 10%

  2. 19%

  3. 20%

  4. 36%

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Area is proportional to the square of the radius. If the radius becomes 0.9r, the area becomes (0.9)^2 = 0.81 of the original area. The decrease is 1 - 0.81 = 0.19, or 19%.

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