The ratio of the radii of two circles is $4: 5$. Then,the ratio of their areas is...........

If the area of a circle is $154 \, cm^2$,then its perimeter (circumference) is (in $cm$):

The length of the minute hand of a clock is $14 \, cm$. If the minute hand moves from $1$ to $10$ on the dial,then $\ldots \ldots \ldots \ldots \, cm^2$ area will be covered.

$A$ chord of a circle of radius $12 \, cm$ subtends an angle of $120^{\circ}$ at the centre. Find the area of the corresponding segment of the circle. (in $cm^2$)
(Use $\pi = 3.14$ and $\sqrt{3} = 1.73$)

In a circle with radius $20 \,cm$,the measures of the angle subtended at the centre for two distinct sectors are $15^{\circ}$ and $90^{\circ}$. Then,the ratio of the areas of those sectors is $\ldots \ldots \ldots$.

The ratio of the areas of the circles with radii $8 \, cm$ and $12 \, cm$ is $\ldots \ldots \ldots \ldots .$