$A$ canal is $300 \,cm$ wide and $120 \,cm$ deep. The water in the canal is flowing with a speed of $20 \,km/h$. How much area will it irrigate in $20 \,minutes$ if $8 \,cm$ of standing water is desired? (in $hectares$)

The volume of a hemisphere with radius $3 \, cm$ is $\ldots \ldots \ldots \pi \, cm^{3}$.

How many cubic centimetres of iron are required to construct an open box whose external dimensions are $36 \, cm$,$25 \, cm$,and $16.5 \, cm$,provided the thickness of the iron is $1.5 \, cm$? If one cubic $cm$ of iron weighs $7.5 \, g$,find the weight of the box.

Water is flowing at the rate of $15\, km/h$ through a pipe of diameter $14\, cm$ into a cuboidal pond which is $50\, m$ long and $44\, m$ wide. In what time will the level of water in the pond rise by $21\, cm$? (in $h$)

If the radius of a sphere is doubled,its volume becomes $\ldots \ldots \ldots$ times the volume of the original sphere.

The volume of a cone is equal to: