The radius of the cylinder is made twice as large. How should the height be changed so that the volume remains the same?

$A$ large solid sphere is melted and moulded to form identical right circular cones with base radius and height same as the radius of the sphere. One of these cones is melted and moulded to form a smaller solid sphere. Then the ratio of the surface area of the smaller to the surface area of the larger sphere is

$A$ metallic sheet is of rectangular shape with dimensions $48\, m \times 36\, m$. From each of its corners, a square is cut off so as to make an open box. If the length of the side of the square is $8\, m$, the volume of the box (in $m^3$) is:

The circumference of the base of a $9\, m$ high conical tent is $44\, m$. The volume of the air contained in it is.........$m^3$

$A$ cylinder,a hemisphere,and a cone stand on the same base and have the same heights. Find the ratio of their volumes and also the ratio of the areas of their curved surfaces.

The base of a right pyramid is a square of side $10 \text{ cm}$. If the height of the pyramid is $12 \text{ cm}$,then its total surface area is ....... $\text{cm}^2$.