$A$ 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 $liters$)

Surface area of a sphere $= \dots \dots \dots \dots .$

Total surface area of a cube open at one end $= \dots$

$A$ cylindrical tank is closed at both the ends by cones of height $12 \, cm$. The diameter of the cylindrical part is $14 \, cm$ and its height is $20 \, cm$. Find the volume of this tank (in $cm^3$).

$A$ cone of radius $8 \, cm$ and height $12 \, cm$ is divided into two parts by a plane through the mid-point of its axis parallel to its base. Find the ratio of the volumes of the two parts.

Water flows through a cylindrical pipe,whose inner radius is $1 \,cm$,at the rate of $80 \,cm/sec$ into an empty cylindrical tank,the radius of whose base is $40 \,cm$. What is the rise of water level in the tank in half an hour? (in $cm$)