The radius of a cone is $15 \, cm$ and its base is hemispherical. If the total height of the solid is $55 \, cm$,find its volume in $cm^3$.

$CSA$ of a hemisphere with diameter $20 \, cm$ is $\ldots \ldots \ldots cm^{2}$. (in $\pi$)

$A$ solid right circular cone of height $120 \,cm$ and radius $60 \,cm$ is placed in a right circular cylinder full of water of height $180 \,cm$ such that it touches the bottom. Find the volume of water left in the cylinder,if the radius of the cylinder is equal to the radius of the cone.

$A$ pen stand made of wood is in the shape of a cuboid with four conical depressions and a cubical depression to hold the pens and pins,respectively. The dimensions of the cuboid are $10 \, cm$,$5 \, cm$,and $4 \, cm$. The radius of each of the conical depressions is $0.5 \, cm$ and the depth is $2.1 \, cm$. The edge of the cubical depression is $3 \, cm$. Find the volume of the wood in the entire stand. (in $, cm^3$)

$A$ metallic sphere with radius $6 \, cm$ is melted and recast into a wire of radius $0.4 \, cm$. Find the length of the wire in metres.

$A$ tank is in the form of a cylinder with radius $21\, cm$ closed at both the ends by hemispheres. If the total height of the tank is $62\, cm$, how many litres of water can it store? (in $liters$)