Multiple choice

Radius of a sphere is increased by 15%. Find the percentage change in its total surface area.

  1. 27.25%

  2. 32.25%

  3. 30.5%

  4. 37.75%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When radius increases by 15%, new radius = 1.15r. Surface area scales with r², so new SA = 4π(1.15r)² = 4π × 1.3225r² = 1.3225 × original SA. Percentage increase = 32.25%.

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