Question

The inner circumference of a circle is 220metre and the track is 7 metre wide everywhere. calculate the cost of putting a fence along the outer circle at the rate of 2 rupees per metre

Answer 1

Given inner cirumference = 220 m

We know that the formula to find out the circumference of a circle is 2πr

So,

$= > 2\pi \: r = 220 \\ \\ = > \frac{44}{7} \times r = 220 \\ \\ = > r = \frac{220 \times 7}{44} \\ \\ = >r = \frac{1540}{44} \\ \\ = > \red{\boxed{ r = 35 \: m}}$

So from the above calculation we find the radius of the inner circle is 35 m

So to find the circumference of the outer circle we need to calculate the outer radius

So, the outer radius is equal to the sum of the radius of inner circle and the width of path around it

•°•Outer radius =( 35+7)= 42 m

So outer circumference

$= > 2\pi \: r = 2 \times \frac{22}{7} \times 42 \\ \\ = > circumference = \frac{44}{7} \times 42 \\ \\ = > circumference = 44 \times 6 \\ \\ = > circumference = 264m$

A/Q,

1 m= Rs 2

So,

$264m = 2 \times 264 \\ \\ = > \boxed{\red{total \: cost \: for \: fencing = \: rs \: 528}}$