2017 · Q74
The areas of two circular fields are in the ratio 16 : 49. If the radius of the bigger field is 14 m, then what is the radius of the smaller field ?
Elementary MathematicsMensuration
- A4 m
- B8 m
- C9 m
- D10 m
Explanation
This uses the area–radius square relation. Areas are in ratio 16:49, and area ∝ r², so radii are in ratio √16:√49 = 4:7. The smaller radius is 14 × 4/7 = 8 m. Option (d) 10 m would come from taking a linear rather than square-root ratio of the areas. Hence option (b).