Question

If the radii of two concentric circles are $15\text{cm}$ and $13\text{cm}$, respectively, then the area of the circulating ring in sq. cm will be:

• A. $176$
• B. $178$
• C. $180$
• D. $200$

Answer 1

The correct option is A $176$

$R=15\text{cm},r=13\text{cm}.$

Area of the circulating ring $=\pi (R^2-r^2)$

$=\frac{22}{7}({15}^2-{13}^2){\text{cm}}^2$

$=\frac{22}{7}\times 28\times 2{\text{cm}}^2$

$=176{\text{cm}}^2$