There are 4 semi-circular gardens on each side of a square-shaped pond with each side 21 m. The cost of fencing the entire plot at the rate of Rs. 12.50 per metre is :

Answer: Option B

Solution

Answer: Option B

Solution:

Length of the fence =$$4\pi R$$
Where, $$R=\frac{21}{2}m$$

$$\begin{array}{rl}& 4\pi R\\ & =\left(4\times \frac{22}{7}\times \frac{21}{2}\right)m\\ & =132m\end{array}$$
Cost of fencing :
$$\begin{array}{rl}& =\text{Rs}\text{.}\left(132\times \frac{25}{2}\right)\\ & =\text{Rs}\text{.1650}\end{array}$$