........ is a unit of area.

The volume of a frustum of a cone is equal to $\ldots \ldots \ldots . .$

$A$ metallic cone with radius $5 \, cm$ and height $8 \, cm$ is melted and recast to produce identical balls with diameter $0.5 \, cm$. Find the number of balls produced.

The radius of a sphere with surface area $\frac{763}{3} \, m^{2}$ is $\ldots \ldots \ldots m$. $(\pi = 3.14)$

$A$ canal is $300 \,cm$ wide and $120 \,cm$ deep. The water in the canal is flowing with a speed of $20 \,km/h$. How much area will it irrigate in $20 \,minutes$ if $8 \,cm$ of standing water is desired? (in $hectares$)

$A$ cylinder is closed at both the ends by $18\, cm$ high cones. The radius of the cylinder is $7\, cm$ and the total height of the solid is $64\, cm$. Find the volume of this solid (in $cm^3$).