Diameter of the circular garden = 21 m
\Radius of the circular garden = 21/2 m
Now
Circumference of circular garden =2 πr
= 2 x 22/7 x 21/2
= 22 x 3 = 66 m
The gardener makes 2 rounds of fence so the total length of the rope of fencing
= 2 x2 πr = 2 x 66 = 132 m
Since the cost of 1 meter rope = Rs 4
Therefore, cost of 132 meter rope = 4 x 132 = Rs 528