Cost of fencing a circular plot at the rate of Rs. 15 per metre is Rs. 3300. What will be the cost of flooring the plot at the rate of Rs. 100 per square metre ?

Circumference of the plot :
$$\eqalign{ & = \left( {\frac{{3300}}{{15}}} \right)m \cr & = 220\,m \cr & \Rightarrow 2\pi R = 220 \cr & \Rightarrow R = \frac{{220 \times 7}}{{2 \times 22}} \cr & \Rightarrow R = 35\,m \cr} $$
Area of the plot :
$$\eqalign{ & = \left( {\frac{{22}}{7} \times 35 \times 35} \right){m^2} \cr & = 3850\,{m^2} \cr} $$
∴ Cost of flooring :
$$\eqalign{ & = {\text{Rs}}{\text{.}}\left( {3850 \times 100} \right) \cr & = {\text{Rs}}{\text{. 385000}} \cr} $$