Volume of a cone $= \dots$

$A$ toy is in the form of a cone surmounted on a hemisphere. The radius of the cone as well as the hemisphere is $3.5\, cm$ and the total height of the toy is $15.5\, cm$. Find its total surface area (in $cm^2$).

$A$ cone and a cylinder have equal radii and equal heights. Then,the ratio of their volumes is $\ldots \ldots \ldots . .$

The diameter of a cylinder is $14\, cm$ and its height is $10\, cm$. Then,the volume of the cylinder is $\ldots \ldots \ldots \ldots cm^3$.

$A$ metallic cylinder with diameter $1 \, cm$ and height $4 \, cm$ is melted and recast to produce balls of radius $\frac{1}{8} \, cm$. Find the number of balls produced.

The volume of a $1-$ rupee coin is given by the formula $\ldots \ldots \ldots . . .$