Question

The cost of fencing a circular garden of radius 21 m at ₹10 per metre is

(a) ₹1320 (b) ₹132 (c) ₹1200 (d) ₹660

Answer 1

Radius (r) = 21 m
Cost per metre = ₹10
Circumference of circle = $2\pi r=2\times \frac{22}{7}\times 21=132\mathrm{m}$
Cost of fencing = Circumference $\text{×}$ Cost per metre
= 132 $\text{×}$ ₹10
= ₹1320
Hence, the correct option is (a).