Difference between radii from circumferences: Two concentric circles have circumferences 176 m and 132 m. Find the difference between their radii.
Aptitude
Area
Difficulty: Easy
Choose an option
-
A5 meter
-
B7 meter
-
C8 meter
-
D44 meter
-
E6 meter
Answer
Correct Answer: 7 meter
Explanation
Introduction / Context:For concentric circles, the difference in circumferences equals 2π times the difference in radii. This allows a one-step computation of the radial gap.
Given Data / Assumptions:
- C1 = 176 m, C2 = 132 m
- ΔC = 44 m
- Δr = ΔC / (2π)
Concept / Approach:Apply the circumference formula in difference form and divide by 2π.
Step-by-Step Solution:Δr = 44 / (2π) = 22 / π = 22 / (22/7) = 7 m
Verification / Alternative check:With π ≈ 3.1416, Δr ≈ 7.0 m; both approximations agree.
Why Other Options Are Wrong:5 m, 6 m, and 8 m are off; 44 m confuses ΔC with Δr.
Common Pitfalls:Dividing by π only (forgetting the factor 2); mixing units or misreading which is the larger circumference.
Final Answer:7 meter