Question

A circular track is made for running exercises whose center is always $70$ m away from the person who is running on the circular track. How many rounds are required for the runner to complete $1.760$ Km running ?$(\pi =\frac{22}{7})$

• A. $8\text{round}$
• B. $4\text{round}$
• C. $3.5\text{round}$
• D. $5\text{round}$

Answer 1

The correct option is B $4\text{round}$

Distance between the person running and the center of circle is the radius of circle which is $70$ cm.
So,
$\text{circumference}=2\pi r$
$\text{circumference}=2\times \frac{22}{7}\times 70$
$\text{circumference}=440$ m

It means the runner will complete $440$ m running in $1$ round.

Let $n$ rounds be required to complete $1.760$ Km running
also, $1.760km=1.760\times 1000m=1760m$

So, $n\times 440=1760$
$n=\frac{1760}{440}$
$n=4$

Hence, total $4$ rounds will be required so, option $\left(b\right)$ correct.