The length of the minute hand of a clock is $6 \, cm$. The area of the region swept by it in $10 \, \text{minutes}$ is $\ldots \ldots \ldots \ldots \, cm^2$. $(\pi = 3.14)$

In a circle with radius $21 \ cm$,the perimeter of a minor sector is $64 \ cm$. Then,the length of the arc of that sector is $\ldots \ cm$.

In a circle with radius $50 \, cm$,the area of the sector formed by a $20 \, cm$ long arc is $\ldots \ldots \ldots cm^2$.

On a square cardboard sheet of area $784 \, cm^{2}$, four congruent circular plates of maximum size are placed such that each circular plate touches the other two plates and each side of the square sheet is tangent to two circular plates. Find the area of the square sheet not covered by the circular plates (in $cm^{2}$).

$A$ chord of a circle of radius $20\, cm$ subtends an angle of $90^{\circ}$ at the centre. Find the area of the corresponding major segment of the circle. (Use $\pi=3.14$) (in $cm^2$)

The ratio of the areas of two circles is $25: 36$. Then,the ratio of their circumferences is: