A square water tank has its side equal to 40 m. There are four semi-circular grassy plots all round it. Find the cost of turfing the plot at Rs. 1.25 per square metre (Take π = 3.14).

#### Solution

It is given that the side of square . `a=40 m`

Since four semicircular grassy plots rounds a square water tank. Then, diameter of semicircular plot is`2r=a`.

So, the radius of semicircle

`r=a/2`

`=40/2`

`20 m`

Area of semicirular plot=`1/2 pir^2`

`= 1/2xx3.14xx20xx20`

`=628 m^2`

Now, the total area of plot is sum of area of four semicircular plots.

`"Total Area of plot"=4xx "Area of semicircle"`

`=4xx628 m^2`

` = 2512 m^2`

Since, The cost of turding the plot per squre meter=`Rs.1.25`

So, The cost turfing 2512 square meter plot= `Rs1.25xx2512`

`= Rs 3140`