Cylinders — Radii in ratio 2:3 and heights in ratio 5:3. Find the ratio of their volumes.
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
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A27 : 20
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B20 : 27
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C4 : 9
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D9 : 4
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E5 : 3
Answer
Correct Answer: 20 : 27
Explanation
Introduction / Context:Volume of a cylinder V = π r^2 h. Ratios multiply across exponents: r contributes squared, h contributes linearly.
Given Data / Assumptions:
- r1:r2 = 2:3
- h1:h2 = 5:3
Concept / Approach:Compute V1:V2 = (r1^2 h1):(r2^2 h2) = (2^2 * 5) : (3^2 * 3).
Step-by-Step Solution:V1:V2 = (4 * 5):(9 * 3) = 20:27
Verification / Alternative check:Plug sample values (e.g., r1=2, r2=3, h1=5, h2=3) to confirm the computed ratio.
Why Other Options Are Wrong:27:20 inverts; 4:9 or 9:4 ignore heights; 5:3 ignores r^2.
Common Pitfalls:Forgetting to square the radius in volume formula.
Final Answer:20 : 27