The ratio of radii of two circles is $3:5$. Find the ratio of their areas

The inner circumference of a circular track is $264 m$ and the width of the track is $7 m$. Calculate the cost of putting up a fence along the outer circle of the track at the rate of $₹3.50$ per metre. (in $₹$)

The inner circumference of a circular track is $264 m$ and the width of the track is $7 m$. The area of the track is $x m^2$. Find the value of $x$.

The circumferences of two concentric circles are $62.8 m$ and $37.68 m$. The area between the circles is $x m^2$. Find the value of $x$?

Four horses are tied at the four corners of a square field of side $35 m$, so that they can just reach to each other. The area of the field which remain ungrazed is $x m^2$. Find the value of $x$?