If the side of a cube is increased by $100 \%$,its volume is increased by (in $\%$)

The radius of a cylinder is $10\, cm$ and its height is $4\, cm$. The value of $x$ (in $cm$) that may be added either to the radius or to the height to get the same increase in the volume of the cylinder is:

$A$ right circular cylinder having diameter $21\, cm$ and height $38\, cm$ is full of ice cream. The ice cream is to be filled in cones of height $12\, cm$ and diameter $7\, cm$ having a hemispherical shape on the top. The number of such cones to be filled with ice cream is

$A$ 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 $cm$)

$A$ hemisphere is made of lead. Its radius is $6 \, cm$. It is cast into a right circular cone of $75 \, cm$ height. The radius of the base of the cone is ......... $cm$.

$3$ equal cubes are placed adjacently in a row. Find the ratio of the total surface area of the new cuboid to the sum of the surface areas of the three cubes.