The volume of a cube is $729 \, cm^3$. The total surface area of the cube is ........ $cm^2$.

The cost of paint is ₹ $36/kg$. If $1\, kg$ of paint covers $1.5\, m^2$,how much will it cost to paint the outside of a cube having a $2.5\, m$ side?

$A$ rectangular plot,$36 \, m$ long and $28 \, m$ broad,has two concrete roads $5 \, m$ wide running in the middle of the park,one parallel to the length and the other parallel to the breadth. What would be the total cost of gravelling the plot,excluding the area covered by the roads,at ₹ $3.60$ per $m^{2}$? (in $Rs.$)

$A$ solid cone of height $36 \, cm$ and radius of base $9 \, cm$ is melted to form a solid cylinder of radius $9 \, cm$ and height $9 \, cm$. What percent of material is wasted in this process (in $\%$)?

$2$ cans have the same height equal to $21\, cm$. One can is cylindrical,the diameter of whose base is $10\, cm$. The other can has a square base of side $10\, cm$. What is the difference between their capacities? (in $cm^3$)

$A$ cylinder,a hemisphere,and a cone stand on the same base and have the same heights. Find the ratio of their volumes and also the ratio of the areas of their curved surfaces.