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Two circles have radii in the ratio 2:3. The ratio of their CIRCUMFERENCES is:
A4:9
B2:3
C3:2
DCannot be determined
Answer & Solution
Correct answer: B. 2:3
Circumference C = 2πr. If r₁/r₂ = 2/3, then C₁/C₂ = (2πr₁)/(2πr₂) = r₁/r₂ = 2/3. Circumference scales LINEARLY with radius. (Note: AREAS scale as the SQUARE of the ratio — areas would be 4:9. That's a common distractor.)
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