Two cubes have volumes in the ratio 8 : 1. Find the ratio of their edges.
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
-
A8 : 1
-
B2√2 : 1
-
C2 : 1
-
DNone of these
Answer
Correct Answer: 2 : 1
Explanation
Introduction / Context:For similar solids (including cubes), volume scales as the cube of the linear dimension. If V1 : V2 = 8 : 1, then (a1/a2)^3 = 8/1, so the edge-length ratio is the cube root of the volume ratio.
Given Data / Assumptions:
- V1 : V2 = 8 : 1.
- V ∝ a^3 for cubes.
Concept / Approach:Take cube roots of both sides of the ratio: (a1/a2) = ∛(8/1) = 2/1.
Step-by-Step Solution:(a1/a2)^3 = 8 ⇒ a1/a2 = 2
Verification / Alternative check:Let a2 = 1 ⇒ V2 = 1; set a1 = 2 ⇒ V1 = 8; ratio holds.
Why Other Options Are Wrong:8 : 1 is a volume ratio; 2√2 : 1 is irrelevant; “None” is unnecessary because 2 : 1 is correct.
Common Pitfalls:Squaring or leaving the ratio unchanged instead of taking cube roots.
Final Answer:2 : 1