For the science fair,a student prepared a model in the shape of a cylinder with radius $10 \,cm$ and height $40 \,cm$,closed at both ends by cones with slant height $26 \,cm$. How many litres of water can it contain?

$A$ mason constructs a wall of dimensions $270 \,cm \times 300 \,cm \times 350 \,cm$ with bricks each of size $22.5 \,cm \times 11.25 \,cm \times 8.75 \,cm$. If $\frac{1}{8}$ of the total volume of the wall is occupied by mortar,find the number of bricks used to construct the wall.

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 $cm$).

The base of a cone with radius $5 \, cm$ and height $12 \, cm$ is hemispherical. Find the total surface area of the article. $(\pi = 3.14)$ (in $cm^2$)

The $CSA$ (Curved Surface Area) of a cylinder is equal to $\ldots \ldots \ldots$

The $TSA$ of a hemisphere with radius $10 \, cm$ is $\ldots \ldots \ldots \, cm^{2}$. (in $\pi$)