Question

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

Answer 1

Lets draw the figure, according to question

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

$\Rightarrow$ Area of the flower beds $1$ and $2$ $=\frac{1}{2}\pi r^2$

$=\frac{1}{2}\times 3.14\times (50m{)}^2$

$=7850m^2$

Therefore, Area of the flower beds $1$ and $2$ $=7850m^2$-------(1)

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

$\Rightarrow$ Area of the flower beds $1$ and $2$ $=\frac{1}{2}\times 3.14\times (25m{)}^2$

$=1962.5m^2$

Therefore, Area of the flower beds $3$ and $4$ $=1962.5m^2$-------(2)

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

$\Rightarrow$ Cost of levelling four flower beds $=9812.5\times 0.60=Rs.5887.50$