Question

A track is in the form of a ring whose inner circumference is $352m$ and the outer circumference is $396m$. The width of the track is:

• A. $44m$
• B. $14m$
• C. $22m$
• D. $7m$

Answer 1

The correct option is D $7m$

Let the radii of inner and outer circles be $r$ and $R$, respectively.
Circumference of inner circle $=352m$
$\therefore 2\pi r=352$

$2\times \frac{22}{7}\times r=352$
$\Rightarrow r=56m$
Similarly, Circumference of outer circle $=396m$
$\therefore 2\pi R=396$

$2\times \frac{22}{7}\times R=396$
$\Rightarrow R=63m$
Now, Width of the track $=R-r$
$=63-56$
$=7m$
So, width of the track $=7m$