Question

A rectangular park is $100m$ by $50m$. It is surrounded by semi-circular flower beds all around. Find the cost of levelling the semi-circular flower beds at $60$ paise per square metre (Use $\pi$ $=3.14$).

Answer 1

$\Rightarrow$ The radius of the flower beds $1$ and $2=\frac{100}{2}=50m$

$\Rightarrow$ Area of the flower beds $1$ and $2$ $=2\times \left(\frac{1}{2}\pi r^2\right)$

$\Rightarrow$ Area of the flower beds $1$ and $2$ $=3.14\times 50\times 50=7850m^2$

$\Rightarrow$ The radius of the flower beds $3$ and $4$ $=\frac{50}{2}=25m$

$\Rightarrow$ Area of the flower beds $3$ and $4$ $=2\times \left(\frac{1}{2}\pi r^2\right)$

$\Rightarrow$ Area of the flower beds $3$ and $4$ $=3.14\times 25\times 25=1962.5m^2$

$\Rightarrow$ Area of the all four flower beds $=7850m^2+1962.5m^2=9812.5$

$\Rightarrow$ Cost of levelling four flower beds $=9812.5\times 0.60=Rs.5887.5$