A spherical balloon is inflated and its radius increases from 5 cm to 10 cm. What is the percentage increase in the surface area?
Show answer & explanation
Correct answer: B
Explanation
Given:
Initial radius = 5 cm
Final radius = 10 cm
By formula:
Surface area of sphere = 4πr²
Initial area = 4π × 5² = 100π
New area = 4π × 10² = 400π
Increase = 400π − 100π = 300π
Percentage increase = (300π / 100π) × 100 = 300%