Question

If circumferences of the outer circle and inner circle are $150$ m and $100$ m respectively. Find the width of the ring?

• A. $\frac{25}{\pi }$
• B. $\frac{25}{3\pi }$
• C. $\frac{25}{2\pi }$
• D. none of these

Answer 1

Answer: (A)

$\frac{25}{\pi }$

Circumference of inner circle=$2\pi r_1$

Circumference of the outer circle= $2\pi r_2$

$2\pi r_1=$100

$r_1=\frac{50}{\pi }$

$2\pi r_2=150$

$r_2=\frac{75}{\pi }$

Width of the ring=$r_2-r_1$

Width of the ring=$\frac{75}{\pi }-\frac{50}{\pi }$

Hence,

the Width of the ring= $\frac{25}{\pi }$.

option A is the answer.