In a right circular cone,the cross-section made by a plane parallel to the base is a

$A$ cylinder with radius $6 \, cm$ is closed at one end by a $8 \, cm$ high cone and is open at the other end. The total height of the article is $20 \, cm$. Find the total surface area of the article. $(\pi = 3.14)$ (in $cm^2$)

$A$ 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 $cm^2$.

........ is a unit of area.

Write 'True' or 'False' and justify your answer:
The capacity of a cylindrical vessel with a hemispherical portion raised upward at the bottom as shown in the figure is $\frac{\pi r^{2}}{3} [3 h-2 r]$.

Marbles of diameter $1.4 \,cm$ are dropped into a cylindrical beaker of diameter $7 \,cm$ containing some water. Find the number of marbles that should be dropped into the beaker so that the water level rises by $5.6 \,cm$.