Question

A race track is in the form of a ring whose inner circumference is 352 m, and the outer the circumference is 396 m. Find the width of the track.

Answer 1

Let the outer and inner radii of the ring be R meters and r metres respectively. Then,

$2\pi R=396\text{and}2\pi r=352$

$\Rightarrow 2\times \frac{22}{7}\times R=396\text{and}2\times \frac{22}{7}\times r=352$

$\Rightarrow R=396\times \frac{7}{22}\times \frac{1}{2}\text{and}r=352\times \frac{7}{22}\times \frac{1}{2}$

R = 63 m and r = 56 m

Hence, width of the track

= (R – r) metres = (63 – 56) metres

= 7 metres.