If a hemisphere is melted and four spheres of equal volume are made,the radius of each sphere will be equal to

The height of the right pyramid whose area of the base is $30\, m^{2}$ and volume is $500\, m^{3}$ is ...... $m$.

$A$ solid cylinder has a base radius of $14\, cm$ and a height of $15\, cm$. Identical small cylinders are cut from each base as shown in the figure. The height of each small cylinder is $5\, cm$ and the radius is $7\, cm$. What is the total surface area (in $cm^2$) of the remaining part?

If three metallic spheres of radii $6\, cm$,$8\, cm$,and $10\, cm$ are melted to form a single sphere,the diameter of the new sphere will be (in $cm$)?

The volume of a cube is $729 \, cm^3$. The total surface area of the cube is ........ $cm^2$.

$A$ hollow cylinder of height $3\,cm$ is recast into a solid cylinder. If the external and internal radii of the hollow cylinder are $4.3\,cm$ and $1.1\,cm$ respectively,what will be the radius of the solid cylinder? (in $cm$)