Calculate the number of bricks,each measuring $25 \, cm \times 15 \, cm \times 8 \, cm$,required to construct a wall with dimensions $19 \, m \times 4 \, m \times 5 \, m$,when $10 \%$ of its volume is occupied by mortar.

It is required to design a circular pipe such that water flowing through it at a speed of $7 \ m/min$ fills a tank of capacity $440 \ m^3$ in $10 \ min$. The inner radius of the pipe should be (in $m$):

$A$ large cube is formed from the material obtained by melting three smaller cubes of $3, 4$ and $5 \, cm$ side. What is the ratio of the total surface areas of the smaller cubes and the large cube?

Three solid spheres have their radii $r_{1}, r_{2}$ and $r_{3}$. The spheres are melted to form a single solid sphere of a bigger radius. The radius of the new sphere is:

$A$ hemisphere is placed on top of a cube. Its front view is shown in the given figure. The total height of the figure is $221 \ cm$. The ratio of the curved surface area of the hemisphere to the total surface area of the cube is $11:42$. What is the total volume (in $cm^3$) of the figure?

$A$ 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