Find the weight of a hollow cylindrical lead pipe $28\, cm$ long and $0.5\, cm$ thick. Its internal diameter is $8\, cm$. (in $kg$) (Weight of $1\, cm^3$ of lead is $11.4\, g$,$\pi = \frac{22}{7}$)

Marbles of diameter $1.4\, cm$ are dropped into a cylindrical beaker containing some water and are fully submerged. The diameter of the beaker is $7\, cm.$ Find how many marbles have been dropped in it if the water rises by $5.6\, cm.$

$A$ solid sphere and a solid hemisphere have the same total surface area. The ratio of their volumes is

$A$ solid cone is $25 \ cm$ high and the radius of its base is $50 \ cm$. It is melted and recast into a solid sphere. Determine the surface area of the sphere (in $cm^2$).

$A$ 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 $\%$)?

$A$ conical vessel of base radius $2 \ cm$ and height $3 \ cm$ is filled with kerosene. This liquid leaks through a hole in the bottom and collects in a cylindrical jar of radius $2 \ cm$. The kerosene level in the jar is.....$cm$