$A$ cone of height $7 \text{ cm}$ and base radius $3 \text{ cm}$ is carved from a rectangular block of wood $10 \text{ cm} \times 5 \text{ cm} \times 2 \text{ cm}$. The percentage of wood wasted is:

$A$ right cylinder and a right circular cone have the same radius and the same volume. The ratio of the height of the cylinder to that of the cone is

How many bricks,each measuring $25\, cm \times 11.25\, cm \times 6\, cm$,will be needed to build a wall $8\, m \times 6\, m \times 22.5\, cm$?

An iron cube of $10\, cm$ sides is hammered into a rectangular sheet of thickness $0.5\, cm$. If the sides of the sheet are in the ratio $1:5$, the sides (in $cm$) are:

$A$ roller is $120 \, cm$ long and has a diameter of $84 \, cm$. If it takes $500$ complete revolutions to level a playground,determine the cost of levelling at the rate of $30 \, \text{paise}$ per $m^2$ (in $Rs.$). (Use $\pi = \frac{22}{7}$)

How many bricks are required to build a $15\, m$ long,$3\, m$ high,and $50\, cm$ thick wall,if each brick measures $25\, cm \times 12\, cm \times 6\, cm$?