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Two circles have diameters in the ratio 3:5. What is the ratio of their areas?

medium MCQ 2 marks Class 8 · Mathematics · Comparing Quantities
  1. 9:25
  2. 5:3
  3. 9:16
  4. 3:5
Answer
9:25

The correct answer is 9:25 — Thus the ratio of the areas is .

Step-by-step solution

  1. Since diameters are 3:5, radii are also 3:5 (radius = diameter/2).
  2. Area of a circle is proportional to the square of its radius.
  3. Square the radius ratio: .
  4. Thus the ratio of the areas is .
Common mistake: Using diameter ratio directly in area formula instead of radius

Concept tested: Ratio of areas from diameter ratio

Published · How this solution was prepared and checked

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