The radius of a sphere with surface area $1256\,cm^{2}$ is $\ldots \ldots \ldots cm$. $(\pi = 3.14)$

$CSA$ of a cylindrical tank with diameter $2.1 \, m$ and height $5 \, m$ is $\ldots \ldots \ldots \ldots \, m^2$.

$A$ tent is in the shape of a cylinder surmounted by a conical top. If the height and diameter of the cylindrical part are $2.1 \, m$ and $4 \, m$ respectively,and the slant height of the top is $2.8 \, m$,find the area of the canvas used for making the tent. Also,find the cost of the canvas of the tent at the rate of $Rs. \, 500$ per $m^2$. (in $Rs.$) [Use $\pi = \frac{22}{7}$] (Note that the base of the tent will not be covered with canvas.)

$2$ cubes each of volume $64 \, cm^3$ are joined end to end. Find the surface area of the resulting cuboid in $cm^2$.

$A$ fez,the cap used by the Turks,is shaped like the frustum of a cone (see $Fig.$). If its radius on the open side is $10 \, cm$,radius at the upper base is $4 \, cm$ and its slant height is $15 \, cm$,find the area of material used for making it.

The area of the base of a cylinder is equal to: