A garden roller has a circumference of $3 \mathrm{meters}$. How many revolutions does it make in moving a distance of $21 \mathrm{meters}?$

The figure shows a running track in which $\mathrm{AF}=\mathrm{CD}=100 \mathrm{m}$ and $\mathrm{FED}$ and $\mathrm{ABC}$ are semi-circles whose diameters $\mathrm{FD} \& \mathrm{AC}$ are equal. If an athlete run in taking one complete round of the track is $k \mathrm{m}$, find the value of $k$

A circular field has a perimeter of $660 \mathrm{m}$. A plot in the shape of square having its vertices on the circumference is marked in the field, then the area of the square plot is $k {\mathrm{m}}^2$, find the value of $k$. Use $\left(\mathrm{\pi }=\frac{22}{7}\right)$

If the area of the circle whose diameter is $7 \mathrm{cm}$ is $k {\mathrm{cm}}^2$, find the value of $k$. Use $\left(\mathrm{\pi }=\frac{22}{7}\right)$

If the area of the circle whose radius is $14 \mathrm{cm}$ is $k {\mathrm{cm}}^2$, find the value of $k$. Use $\left(\mathrm{\pi }=\frac{22}{7}\right)$