Area of a circle from its circumference — Aptitude Question
Area of a circle from its circumference: The circumference of a circle is 44 cm. What is its area? (Take π = 22/7.) Answer and worked solution on CodeKairo.
- Topic: Mensuration
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 40 seconds
Question
The circumference of a circle is 44 cm. What is its area? (Take π = 22/7.)
Options
- 144 cm²
- 154 cm²
- 164 cm²
- 176 cm²
Show the answer and the worked solution
Correct answer: B. 154 cm²
Worked solution
- 2 × 22/7 × r = 44 → r = 7 cm.
- Area = 22/7 × 49 = 154 cm².
Answer: 154 cm².
The idea
With π = 22/7, radii that are multiples of 7 make everything cancel. Circumference 44 ↔ r = 7 ↔ area 154 is worth remembering.
Shortcut. Area = C² ÷ (4π) = 44 × 44 × 7 ÷ 88 = 22 × 7 = 154 cm², straight from the circumference.
Common trap. 144 cm² — misremembering the stock r = 7 circle area as the familiar square 12²; 22/7 × 49 = 154.