The volume of a sphere is equal to $\ldots \ldots \ldots . .$

$A$ metallic sphere of radius $21 \,cm$ is melted and recast to form a wire with diameter $0.5 \,cm$. Find the length of the wire in $m$.

For the science fair,a student prepared a model in the shape of a cylinder with radius $10 \,cm$ and height $40 \,cm$,closed at both ends by cones with slant height $26 \,cm$. How many litres of water can it contain?

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

$A$ solid consisting of a right circular cone of height $120\, cm$ and radius $60\, cm$ standing on a hemisphere of radius $60\, cm$ is placed upright in a right circular cylinder full of water such that it touches the bottom. Find the volume of water left in the cylinder,if the radius of the cylinder is $60\, cm$ and its height is $180\, cm$. [Take $\pi = \frac{22}{7}$.] (in $m^3$)

$A$ metallic sphere of radius $6 \, cm$ is melted and recast into a wire with diameter $1 \, cm$. Find the length of the wire in metres.