The radius and height of a cylindrical coin are $1.4 \, cm$ and $0.1 \, cm$ respectively. $60$ such coins are stacked up to make a larger cylindrical pillar. Find the volume of this larger cylinder (in $cm^3$).

The volumes of two spheres are in the ratio $64: 27$. Find the ratio of their surface areas.

The radii of three out of four spheres are $33 \, cm$,$44 \, cm$,and $48 \, cm$ respectively. If the surface area of the fourth sphere is equal to the sum of the surface areas of the first three spheres,find the radius of the fourth sphere (in $cm$).

The radii of three metal spheres are $3 \,cm, 4 \,cm$ and $5 \,cm$ respectively. They are melted into a single solid sphere. Find the radius of the new solid sphere (in $cm$).

The diameter of a solid hemisphere is $7 \, cm$. Find its curved surface area and total surface area (in $cm^2$).

The radius of the base of a cone is $7 \, cm$ and its height is $30 \, cm$. Find the volume of a cone (in $cm^3$).