A circular disc's radius is decreased by 10%. What is the percentage decrease…
2025
A circular disc's radius is decreased by 10%. What is the percentage decrease in its area?
- A.
10%
- B.
19%
- C.
18%
- D.
15%
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Correct answer: B
If the radius becomes 90% of the original, the area becomes 0.9 x 0.9 = 0.81 of the original. Hence the decrease is 19%.