Question

The diameter of a circular park is 84 m. On its outside there is a 3.5 m wide round. Find the cost of constructing the roud at Rs.240 per $m^2$.

Answer 1

Diameter $=84$ m, Radius $=42$ m

Outer radius $=42+3.5$ m $=45.5$ m

Outer area from center = $\pi R^2$

$=3.14\times (45.5{)}^2$

$=6500.58m^2$

Inner area = $\pi r^2=3.14\times 42\times 42$

$=5538.96m^2$

Area of round = $(6500.58-5538.96)m^2=961.62m^2$

Cost of construction = Rs. $2.40per{m}^2$

$\therefore$ cost of construction = Rs. $2.40\times 961.62$

$=Rs.2307.88.$