Cylinders — Radii in ratio 2:3 and heights in ratio 5:3. Find the ratio of their volumes.

Difficulty: Easy

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

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