$A$ right circular cylindrical tunnel of diameter $5\, m$ and length $10\, m$ is to be constructed from a sheet of iron. The area of iron sheet required will be..........$\pi\, m^2$.

$A$ solid consists of a circular cylinder with an exact fitting right circular cone placed on the top. The height of the cone is $h$. If the total volume of the solid is three times the volume of the cone,then the height of the cylinder is

The radius of a cylinder is the same as that of a sphere. Their volumes are equal. The height of the cylinder is

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

The capacity of a cylindrical tank is $246.4$ litres. If the height is $4$ metres,what is the diameter of the base? (in $m$)

$A$ solid cone of height $24 \, cm$ and base radius $8 \, cm$ is melted to form a solid cylinder of radius $6 \, cm$ and height $6 \, cm$. In the whole process,what percent of material is wasted (in $\%$)?