2015 · Q49
The ratio of the outer and inner perimeters of a circular path is 23 : 22. If the path is 5 m wide, the diameter of the inner circle is
Elementary MathematicsMensuration
- A55 m
- B110 m
- C220 m
- D230 m
Explanation
This is a concentric-circles ratio problem. The perimeters are in ratio 23:22, so the radii are too: R/r = 23/22. The path width is R - r = 5 m, so r/22 = 5 and r = 110 m. The inner diameter is 2 × 110 = 220 m. Option (b) 110 m is the trap — it is the radius, while the question asks for the diameter. Hence option (c).