2017 · Q88
The radius of a circle is increased so that its circumference increases by 15%. The area of the circle will increase by
Elementary MathematicsMensuration
- A31.25%
- B32.25%
- C33.25%
- D34.25%
Explanation
This tests successive percentage change on area. A 15% circumference increase means r → 1.15r, so the area scales by 1.15² = 1.3225 — a 32.25% increase. Option (a) 31.25% is the near-miss from rounding 1.15². Hence option (b).