$A$ river $3 \,m$ deep and $40 \,m$ wide is flowing at the rate of $2 \,km$ per hour. How much water will fall into the sea in a minute (in $,m^3$)?

$A$ solid cube of side $12 \, cm$ is cut into eight cubes of equal volume. What will be the side of the new cube? Also,find the ratio between their surface areas.

Shanti Sweets Stall was placing an order for making cardboard boxes for packing their sweets. Two sizes of boxes were required. The bigger of dimensions $25 \,cm \times 20 \,cm \times 5 \,cm$ and the smaller of dimensions $15 \,cm \times 12 \,cm \times 5 \,cm$. For all the overlaps,$5\%$ of the total surface area is required extra. If the cost of the cardboard is $Rs. 4$ for $1000 \,cm^2$,find the cost of cardboard required for supplying $250$ boxes of each kind.

The height and the slant height of a cone are $21 \, cm$ and $28 \, cm$ respectively. Find the volume of the cone. (in $, cm^3$)

$A$ dome of a building is in the form of a hemisphere. From inside,it was white-washed at the cost of $Rs. 4989.60$. If the cost of white-washing is $Rs. 20$ per square metre,find the volume of the air inside the dome. (in $, m^3$)

$A$ small indoor greenhouse (herbarium) is made entirely of glass panes (including base) held together with tape. It is $30 \, cm$ long,$25 \, cm$ wide,and $25 \, cm$ high. How much tape is needed for all the $12$ edges (in $, cm$)?