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!!

There are two circles according to the question :

Inner circle :

Circumference = 330 m

Formula = ( 2 ) ( π ) ( r )

2πr = 330

πr = 165

( 22 ÷ 7 ) r = 165

r = ( 165 ) ( 7 ÷ 22 )

r = 52.5

Now, the radius of the outer circle would be

52.5 + 10.5

63m

Find the circumference :

2πr

2 ( 22 ÷ 7 ) ( 63 )

( 2 ) ( 22 ) ( 9 )

( 18 ) ( 22 )

396 m

1 m = 20 rupees

396 m ( 20 ) ( 396 ) rupees

= rupees 7920

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