The shape of a gilli,in the gilli-danda game (see figure),is a combination of

$A$ 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 $hectares$)

Water flows through a cylindrical pipe,whose inner radius is $1 \,cm$,at the rate of $80 \,cm/sec$ into an empty cylindrical tank,the radius of whose base is $40 \,cm$. What is the rise of water level in the tank in half an hour? (in $cm$)

How many balls of radius $1.4 \, cm$ can be produced by melting a metallic sphere of radius $42 \, cm$?

The base of a cone with radius $6 \, cm$ and height $8 \, cm$ is hemispherical. Find the curved surface area and the volume of the solid. $(\pi = 3.14)$

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.