$A$ 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 $cm^2$.

Total surface area of a cuboid measuring $15\,cm \times 12\,cm \times 10\,cm$ is $\ldots \ldots \ldots \,cm^{2}$.

From a solid cylinder whose height is $2.4 \, cm$ and diameter is $1.4 \, cm$,a conical cavity of the same height and same diameter is hollowed out. Find the total surface area of the remaining solid to the nearest $cm^2$. [Take $\pi = \frac{22}{7}$]

The curved surface area $(CSA)$ of a cone is $\ldots \ldots$

The radius and the height of a cylinder are $28 \, cm$ and $54.5 \, cm$ respectively. It is closed at one end by a hemisphere and at the other end by a $21 \, cm$ high cone. Find the total surface area of the combined article. (in $cm^2$)

$A$ container,opened from the top and made up of a metal sheet,is in the form of a frustum of a cone of height $16 \, cm$ with radii of its lower and upper ends as $8 \, cm$ and $20 \, cm$,respectively. Find the cost of the milk which can completely fill the container,at the rate of $Rs. \, 20$ per litre. Also,find the cost of the metal sheet used to make the container,if it costs $Rs. \, 8$ per $100 \, cm^2$. (Take $\pi = 3.14$)