Find the curved surface area of a cone with radius $7 \, cm$ and height $24 \, cm$. (in $cm^2$)

$A$ cuboidal water tank is $2\, m$ long,$1\, m$ wide,and $80\, cm$ deep (height). Its remaining five surfaces,excluding the base,are covered with square tiles of size $20\, cm \times 20\, cm$. Find the number of tiles required.

The radius and slant height of a conical vessel are $21 \,cm$ and $29 \,cm$ respectively. What is its capacity in litres?

The surface area of a sphere is $7850 \, cm^2$. Find its radius in $cm$. (Use $\pi = 3.14$)

In a cylinder,if the radius is doubled and the height is halved,the curved surface area will be:

The total surface area of a cube is $864 \, cm^2$. Then its edge is $\ldots \ldots \ldots \, cm$.