The dome of a building is in the form of a hemisphere. Its radius is $4.2 \, m$. Find the cost of painting it at the rate of ₹ $18$ per $m^2$. (in ₹)

The radius and height of a cylinder are $10\,cm$ and $30\,cm$ respectively. Find the cost of painting its outer curved surface at the rate of ₹ $3$ per $cm^2$. (Use $\pi = 3.14$)

$A$ cylindrical container of radius $14\, cm$ is partially filled with water. $A$ solid cuboid of iron with dimensions $22\, cm \times 16\, cm \times 7\, cm$ is submerged in it. Find the rise in the level of the water when the solid is completely submerged. (in $cm$)

The ratio of the surface area of a sphere to the curved surface area of a hemisphere is $9:2$. Find the ratio of their volumes.

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

The number of planks of dimensions $(4 \,m \times 50 \,cm \times 20 \,cm)$ that can be stored in a pit which is $16 \,m$ long,$12 \,m$ wide,and $4 \,m$ deep is: