Question

A gardener wants to fence a circular garden of diameter $21m$. Find the length of the rope he needs to purchase, if he makes $2$ rounds of fence. Also find the cost of the rope, if it costs $₹4$ per meter. (Take $\pi =\frac{22}{7}$)

Answer 1

Step1: Find the length of the rope

We know that,

radius $\left(r\right)=\frac{d}{2}$

$$\begin{gathered} =\frac{21}{2} \\ =10.5m \end{gathered}$$

Also, Circumference of the circle $=2\mathrm{\pi r}$

$$\begin{gathered} =2\times \frac{22}{7}\times 10.5 \\ =\frac{462}{7} \\ =66m \end{gathered}$$

So, the length of rope required $=2\times 66=132m$ as we need two rounds of fence.

Step2: Find the cost of the rope

Cost of $1m$ rope = $₹4$

Cost of $132m$ rope = $₹4\times 132$

$=528$

Hence,

Length of rope = $132m$

Cost of the rope= ₹ $528$