The ratio of diameters of two cones is $2:3$ and the ratio of their heights is $9:4$. Then,the ratio of their volumes is:

$A$ cylindrical tank with radius $8.4 \,cm$ is closed at one end by a hemisphere. If the total height of the tank is $52.8 \,cm$,how many litres of petrol can it contain (in $.088$)? (in $litres$)

$A$ 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.

$A$ drinking glass in the shape of a frustum of a cone has radii $3\,cm$ and $2\,cm$. If its height is $21\,cm$,its capacity is $\ldots \ldots \ldots cm^{3}$.

The volume of a cylinder is $20 \pi \, cm^3$ and its height is $5 \, cm$. Then,the diameter of the cylinder is $\ldots \ldots \ldots \ldots \, cm$.

$A$ 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 $litres$)