A garden wants to fence a …

<div itemprop="description">Complete step by step solution:
Diameter of a circular garden = 21 m
Radius of a circular garden = <nobr aria-hidden="true">Diameter/2 = 21/2</nobr>m
To find the length of the rope he needs to purchase, if he makes 2 rounds of fence, we need to find the circumference of the circular garden.
Circumference of the circular garden = <nobr aria-hidden="true">2πr </nobr>= <nobr aria-hidden="true">2×22/7×21/2</nobr>$\mathrm{2 }$= 66 m
Circumference of the circular garden is 66 m then it means to fence the garden once the gardener needs 66 m of rope.
To fence the garden twice = 2 X circumference of a circular garden
 = 2 X 66 = 132 m
Length of the rope gardener needs to purchase for fencing two rounds = 132 m (Ans.)
Cost of one meter of rope = Rs. 4
Cost of 132 m of rope = 132 X 4 = Rs. 528</div>