The radii of two cylinders are in the ratio $3:2$ and their heights are in the ratio $8:11$. The ratio of their volumes is....... .

Find the volume of a hemisphere with a diameter of $12 \, cm$. (Use $\pi = 3.14$) (in $cm^3$) (in $.16$)

The front compound wall of a house is decorated by wooden spheres of diameter $21\, cm,$ placed on small supports as shown in the figure. Eight such spheres are used for this purpose,and are to be painted silver. Each support is a cylinder of radius $1.5\, cm$ and height $7\, cm$ and is to be painted black. Find the cost of paint required if silver paint costs $25$ paise per $cm^{2}$ and black paint costs $5$ paise per $cm^{2}.$

Find the volume of a sphere with radius $2.1 \, m$ (in $m^{3}$).

$1$ hectare $= \ldots \ldots \text{ } m^{2}$

Find the curved surface area,total surface area and volume of a hemisphere of diameter $42\, cm$.