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A circular running track is 10 m wide. The difference in the length of the outer boundary and the inner boundary
I. depends on the length of the track
II. depends on the radius of the inner boundary
III. depends on the area of the track
IV is \( \Large 20 \pi m \).
Select the correct answer using the codes below:
Codes :

A) I, II and III
B) I and III
C) II and III
D) IV alone

Correct Answer:




D) IV alone

Description for Correct answer:
If \( \Large r_{1} \) be the radius of the inner boundary, then radius of outer boundary

\( \Large r_{2} = \left(r_{1}+10\right) \)

Difference between length of outer boundary and inner boundary

= \( \Large 2 \pi \left(r_{2}-r_{1}\right) = 2 \pi \left(r_{2}-r_{1}\right) \)

= \( \Large 2 \pi \times 10 = 20 \pi m \)

Part of solved Loci and concurrency questions and answers : >> Elementary Mathematics >> Loci and concurrency

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