Question

A running track is a circular ring of outer diameter 168m .The track is 7m wide. Find circumference of the inner ring.

Answer 1

Diameter of Circular Ring = 168m
So, Radius = 84m

Now, the width of the path = 7m
So the Radius of it will be = 84m + 7m
= 91m

Now, Circumference of circle
$= 2\pi \: r \\ =2 \times \frac{22}{7} \times 91 \\ = 572m$

Answer 2

Answer:

484 m

Step-by-step explanation:

Outer diameter = 168 m

Outer radius = $\frac{Diameter}{2}$

Outer radius = $\frac{168}{2}= 84 m$

Width of track = 7 m

Inner Radius = 84 m - 7 m = 77 m

Inner circumference = $2 \pi r$

Inner circumference = $2 \times \frac{22}{7} \times 77$

Inner circumference = $484 m$

Hence circumference of the inner ring is 484 m