Curved surface of a cylinder — Mensuration Aptitude Question
Curved surface of a cylinder: What is the curved surface area of a cylinder with radius 7 cm and height 10 cm? Answer and worked solution on CodeKairo.
- Topic: Mensuration
- Section: Quantitative Aptitude
- Difficulty: Medium
- Time target: 60 seconds
Question
What is the curved surface area of a cylinder with radius 7 cm and height 10 cm? (Take π = 22/7.)
Options
- 220 cm²
- 308 cm²
- 440 cm²
- 748 cm²
Show the answer and the worked solution
Correct answer: C. 440 cm²
Worked solution
- CSA = 2 × (22/7) × 7 × 10 = 2 × 22 × 10 = 440 cm².
Answer: 440 cm².
The idea
Curved surface is 2πrh; adding the two circular ends gives the total surface 2πr(r + h). Read which one the question wants.
Shortcut. For r = 7, 2πr is 44; multiply by the height: 44 × 10 = 440.
Common trap. 748 cm² — adding the two circular ends (2πr(r + h) = 44 × 17), which is the total surface, not the curved one.