If the circumference of a circle and the perimeter of a square are equal then

Assume $\left[\mathrm{\pi }=\frac{22}{7}\right]$

The radii of two concentric circles are $19 \mathrm{cm}$ and $16 \mathrm{cm}$ respectively. The area of the ring enclosed by these circle is

The areas of two concentric circles are $1386 {\mathrm{cm}}^2$ and $962.5 {\mathrm{cm}}^2$. The width of the ring is

$\left[\text{Take} \mathrm{\pi }=\frac{22}{7}\right]$

In making $1000$ revolutions, a wheel covers $88 \mathrm{km}$. The diameter of the wheel is 

[Take $\mathrm{\pi }=\frac{22}{7}$]