$1 \text{ litre} = \dots \text{ cm}^3$

$A$ container shaped like a right circular cylinder having diameter $12 \, cm$ and height $15 \, cm$ is full of ice cream. The ice cream is to be filled into cones of height $12 \, cm$ and diameter $6 \, cm$,having a hemispherical shape on the top. Find the number of such cones which can be filled with ice cream. [Take $\pi = \frac{22}{7}$]

The volume of a hemisphere with radius $3 \, cm$ is $\ldots \ldots \ldots \pi \, cm^{3}$.

Water in a canal,$6 \, m$ wide and $1.5 \, m$ deep,is flowing with a speed of $10 \, km/h$. How much area will it irrigate in $30 \, minutes$,if $8 \, cm$ of standing water is needed?

From a solid cube of side $7 \, cm$,a conical cavity of height $7 \, cm$ and radius $3 \, cm$ is hollowed out. Find the volume of the remaining solid (in $cm^3$).

$A$ metallic sphere with radius $42\, cm$ is melted to cast $8000$ identical balls. Find the radius of these balls (in $cm$).