The radius of a cylinder is half its height and the curved surface area is $616 \, cm^{2}$. Approximately how many litres of milk can it contain?

$A$ semicircular sheet of metal of diameter $28 \, cm$ is bent into an open conical cup. The capacity of the cup (taking $\pi = \frac{22}{7}$) is (in $cm^3$):

$A$ cylindrical tower is $5 \, m$ in diameter and $14 \, m$ high. The cost of white washing its curved surface at $50$ paise per $m^{2}$ is (in $Rs.$)

$A$ 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 $\%$)?

$A$ cone of height $7 \text{ cm}$ and base radius $3 \text{ cm}$ is carved from a rectangular block of wood $10 \text{ cm} \times 5 \text{ cm} \times 2 \text{ cm}$. The percentage of wood wasted is:

How many coins,$2 \, mm$ thick and $1.5 \, cm$ in diameter,should be melted in order to form a right circular cylinder with base diameter $6 \, cm$ and height $8 \, cm$?