The hollow sphere,in which the circus motorcyclist performs his stunts,has a diameter of $7 \,m$. Find the area available to the motorcyclist for riding. (in $,m^2$)

Find the total surface area of a cone,if its slant height is $21 \, m$ and diameter of its base is $24 \, m$. (Take $\pi = \frac{22}{7}$) (in $, m^2$)

$A$ cubical box has each edge $10\, cm$ and another cuboidal box is $12.5\, cm$ long, $10\, cm$ wide and $8\, cm$ high. Which box has the smaller total surface area and by how much (in $ cm^2$)?

The diameter of a roller is $84\, cm$ and its length is $120\, cm$. It takes $500$ complete revolutions to move once over to level a playground. Find the area of the playground in $m^2$. $\left[\text{Assume } \pi = \frac{22}{7}\right]$ (in $, m^2$)

Find the capacity in litres of a conical vessel with radius $7 \, cm$ and slant height $25 \, cm$. (in $, l$)

$A$ shot-put is a metallic sphere of radius $4.9 \, cm$. If the density of the metal is $7.8 \, g/cm^3$,find the mass of the shot-put. (in $, kg$)