The $TSA$ (Total Surface Area) of a hemisphere is equal to $\ldots \ldots \ldots$

The earth dug out by digging a well with diameter $5.4 \, m$ and depth $20 \, m$ is uniformly spread on a circular ground with radius $15 \, m$. Find the increase in the level of the ground in $cm$.

$A$ metallic spherical shell of internal and external diameters $4 \, cm$ and $8 \, cm$,respectively,is melted and recast into the form of a cone of base diameter $8 \, cm$. The height of the cone is (in $cm$):

$A$ container is in the form of a cylinder closed at one end by a hemisphere. The radius of the cylinder is $8.4 \,cm$ and the total height of the container is $52.8 \,cm$. How many litres of petrol can this container hold? (in $litres$)

The base of a cone is in the shape of a ..............

$A$ solid metallic sphere of radius $10.5 \, cm$ is melted and recast into a number of smaller cones,each of radius $3.5 \, cm$ and height $3 \, cm$. Find the number of cones so formed.