If a regular hexagon is inscribed in a circle of radius $r,$ then its perimeter is........$r$.

Wheels of diameters $7\, cm$ and $14\, cm$ start rolling simultaneously from $X$ and $Y$,which are $1980\, cm$ apart,towards each other in opposite directions. Both of them make the same number of revolutions per second. If both of them meet after $10\, seconds$,the speed of the smaller wheel is.........$cm/sec$.

$A$ circular disc of area $0.49 \pi \, m^2$ rolls down a length of $1.76 \, km$. The number of revolutions it makes is:

The length and breadth of a rectangular piece of land are in the ratio $5:3$. The owner spent ₹ $6000$ for fencing it from all sides at the rate of ₹ $7.50$ per metre. The difference between its length and breadth is (in metres):

$A$ figure consists of a square of side '$a$' $m$ with semi-circles drawn on the outside of the square. The area (in $m^{2}$) of the figure so formed will be

The surface area of a spherical part of a bowl with a flat circular detachable cover,excluding the cover,is $616 \, cm^2$. The area of the cover is $38.5 \, cm^2$. What is the volume of the bowl? (in $cm^3$)