Question

the outer edge of a circular running track is 330 metre long if it is widened by 7 metre around find the cost of widening it at rupees 8 per metre square ​

Answer 1

Perimeter of track =2πr

2πr=440m

u=

44

440×7

=76m

Radius of road=70+5=75m

Area of road =πr

2

=

7

22

×75×75

=17678.57m

2

Area of track=πr

2

=

7

22

×70×70m

2

=220×70m

2

=15400m

2

Area of widening road= Area of road − Area of track

=17678.57−15400

=2278.57m

2

1m

2

costs =Rs. 8/−

2278.57 costs =Rs. 8×2278.57/-

=Rs. 18228.56.