$A$ 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 inside surface area of the dome. (in $, m^2$)

Parveen wanted to make a temporary shelter for her car by making a box-like structure with tarpaulin that covers all the four sides and the top of the car (with the front face as a flap which can be rolled up). Assuming that the stitching margins are very small,and therefore negligible,how much tarpaulin would be required to make the shelter of height $2.5 \, m$,with base dimensions $4 \, m \times 3 \, m$ (in $m^2$)?

Find the radius of a sphere whose surface area is $154 \, cm^2$. (in $, cm$)

$A$ metal pipe is $77 \, cm$ long. The inner diameter of a cross section is $4 \, cm$ and the outer diameter is $4.4 \, cm$ (see Fig.). Find its total surface area. (in $, cm^2$)

Find how much steel was actually used to make a closed cylindrical tank (radius $2.1 \text{ m}$, height $4.5 \text{ m}$), if $1/12$ of the steel actually used was wasted in making the tank. [Assume $\pi = 22/7$] (in $\text{ m}^2$)

$A$ cubical box has each edge $10\, cm$ and another cuboidal box is $12.5\, cm$ long, $10\, cm$ wide and $8\, cm$ high. Which box has the smaller total surface area and by how much (in $ cm^2$)?