The radius of a hemispherical dome of a temple is $21\, m$. Find the cost of painting its outer surface at the rate of ₹ $80/m^2$. (in ₹)

The $TSA$ (Total Surface Area) of a hemisphere is equal to $\ldots \ldots \ldots$

$A$ metallic cylinder with diameter $1 \, cm$ and height $4 \, cm$ is melted and recast to produce balls of radius $\frac{1}{8} \, cm$. Find the number of balls produced.

$A$ funnel (see figure) is the combination of

The radii of two $10 \, cm$ high metallic cylinders are $3.5 \, cm$ and $7 \, cm$. These cylinders are melted and recast to produce a cylinder with height $50 \, cm$. Find the radius of this new cylinder (in $cm$).

$A$ cylinder is closed at both the ends by $28 \, cm$ high cones. The radius and the height of the cylinder are $21 \, cm$ and $50 \, cm$ respectively. Find the total surface area of the article in $cm^2$.