The perimeter of a semicircular protractor of Nitish is $36 \mathrm{cm}$. If its diameter is $k \mathrm{cm}$, then find the value of $k$ considering $\mathrm{\pi }=\frac{22}{7}$.

Dhanno is driving a cart. A wheel of the cart is making $6$ revolutions per second. If the diameter of the wheel is $42 \mathrm{cm}$ and the speed of the cart is $k \mathrm{cm}/\sec$ then find $k$ considering $\mathrm{\pi }=\frac{22}{7}$.

The circumference of the Chakra of National flag exceeds its diameter by $16.8 \mathrm{cm}$. If the radius of the chakra is $k \mathrm{cm}$, then find $k$. $($Take $\mathrm{\pi }=\frac{22}{7})$(Write the answer in decimals)