Cylinders (equal volumes) — Two cylinders have equal volume and heights in ratio 1:2. What is the ratio of their radii?
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
-
A1 : √2
-
B√2 : 1
-
C1 : 2
-
D1 : 4
-
E2 : 1
Answer
Correct Answer: √2 : 1
Explanation
Introduction / Context:Equal volumes with different heights imply different radii. Since V = π r^2 h, the radius must compensate inversely with the square root.
Given Data / Assumptions:
- V1 = V2
- h1:h2 = 1:2
Concept / Approach:From π r1^2 h1 = π r2^2 h2 ⇒ r1^2 / r2^2 = h2 / h1 ⇒ r1 / r2 = √(h2/h1) = √2.
Step-by-Step Solution:r1:r2 = √2:1
Verification / Alternative check:Test with h1=1, h2=2, r1=√2, r2=1 gives equal volumes.
Why Other Options Are Wrong:1:√2 flips the correct ratio; 1:2 or 1:4 treat radius linear with height, not square root.
Common Pitfalls:Missing the square on r in V = πr^2h.
Final Answer:√2 : 1