The diameter of the moon is approximately one-fourth of the diameter of the earth. Find the ratio of their surface areas.

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 $, m^2$)

Find the volume of a sphere whose surface area is $154 \, cm^2$.

Find the volume of the right circular cone with radius $6 \, cm$ and height $7 \, cm$. Assume $\pi = \frac{22}{7}$. (in $, cm^3$)

Diameter of the base of a cone is $10.5\, cm$ and its slant height is $10\, cm$. Find its curved surface area. Assume $\pi = \frac{22}{7}$. (in $, cm^2$)

Find how much steel was actually used to make a closed cylindrical tank (radius $2.1 \text{ m}$, height $4.5 \text{ m}$), if $1/12$ of the steel actually used was wasted in making the tank. [Assume $\pi = 22/7$] (in $\text{ m}^2$)