The surface area of a sphere having radius 7 cm is:

Question

The surface area of a sphere having radius 7 cm is:

1. A. 154 cm²
2. B. 616 cm² (Correct answer)
3. C. 309 cm²
4. D. None of the above

Correct Answer

Option B — 616 cm²

Detailed Solution & Explanation

The correct answer is 616 cm².

Key Points

• The surface area of a sphere is 4πr².
• With r = 7 and π taken as 22/7: 4 × (22/7) × 7 × 7 = 4 × 22 × 7 = 616 cm².

Additional Information

• The distractor 154 cm² is πr², the area of a circle of the same radius — a quarter of the sphere's surface area.
• Related formulas: sphere volume = (4/3)πr³; hemisphere curved surface = 2πr² and total surface = 3πr².
• Choosing r = 7 is deliberate: it cancels the 7 in 22/7 and keeps the arithmetic clean, so expect radii of 7, 14 or 21 in such questions.