WAEC 2016 Mathematics · Question 24
The curve surface area of a cylinder, 5cm high is 110cm 2. Find the radius of its base. [Take ]
Options
- A.2.6cm
- B.3.5cm
- C.3.6cm
- D.7.0cm
Answer: B. 3.5cm
Explanation written with AI and checked against the answer key
Analyze the question: We are given a cylinder with height h = 5 cm and curved surface area = 110 cm². We need the radius r. Concept: The curved surface area of a cylinder is CSA = 2πrh Solution: 110 = 2 × (22/7) × r × 5 110 = (220/7) r r = 110 × 7 / 220 r = 770 / 220 r = 3.5 cm Check: 2 × (22/7) × 3.5 × 5 = 2 × 22 × 0.5 × 5 = 110 ✓ Tip: When π = 22/7 is given, look for a radius that is a multiple of 7 or 3.5 so the 7 cancels neatly. Also remember to use the curved surface formula 2πrh, not the total surface area 2πr(r + h), which would include the two circular ends.AI can make mistakes. Report anything that looks wrong.
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