Question

The inner circumference of a circular track is 330m.The track is 10.5m wide everywhere.Calculate the cost of putting up a fence along the outer circle at the rate of Rs 20 per metre.

Answer 1

Hey there!

Inner circumference of a circle = 330 m.

Circumference= 2πr = 330

2πr = 330

22/7 × r = 165 

r = 165 × 7/22

r = 1155/22 = 52.5 m.


The track is 10.5 m wide. So, outer radius = 52.5 + 10.5 = 63 m.

Thus,
Circumference of outer circle = 2πr

= 2 × 22/7 × 63

= 396 m.

Cost of fencing = Rs. 20/m.

So, cost of fencing 308 m ....

= 396 × 20

= 7920

Hence, 
The cost of fencing is Rs. 7920.