2019 · Q73
The volume of a spherical balloon is increased by 700%. What is the percentage increase in its surface area?
Elementary MathematicsMensuration
- A300%
- B400%
- C450%
- D500%
Explanation
Volume up 700% means V' = 8V, so r' = 2r. Surface area scales as r^2, becoming 4 times — a 300% increase.