Find the volume of the right circular cone with radius $3.5 \, cm$,height $12 \, cm$. Assume $\pi = \frac{22}{7}$. (in $, cm^3$)

The front compound wall of a house is decorated by wooden spheres of diameter $21 \, cm,$ placed on small supports as shown in the figure. Eight such spheres are used for this purpose,and are to be painted silver. Each support is a cylinder of radius $1.5 \, cm$ and height $7 \, cm$ and is to be painted black. Find the cost of paint required if silver paint costs $25$ paise per $cm^2$ and black paint costs $5$ paise per $cm^2$.

The floor of a rectangular hall has a perimeter of $250\, m$. If the cost of painting the four walls at the rate of $10$ per $m^2$ is $Rs. 15000$,find the height of the hall. (in $, m$)

$A$ dome of a building is in the form of a hemisphere. From inside,it was white-washed at the cost of $Rs. 4989.60$. If the cost of white-washing is $Rs. 20$ per square metre,find the volume of the air inside the dome. (in $, m^3$)

The capacity of a closed cylindrical vessel of height $1 \, m$ is $15.4$ litres. How many square metres of metal sheet would be needed to make it (in $, m^{2}$)?

$A$ soft drink is available in two packs: $(i)$ a tin can with a rectangular base of length $5 \, cm$ and width $4 \, cm$ having a height of $15 \, cm$,and $(ii)$ a plastic cylinder with a circular base of diameter $7 \, cm$ and height $10 \, cm$. Which container has greater capacity and by how much (in $, cm^3$)?