$A$ corn cob (see figure),shaped somewhat like a cone,has the radius of its broadest end as $2.1\, cm$ and length (height) as $20\, cm$. If each $1\, cm^2$ of the surface of the cob carries an average of four grains,find how many grains you would find on the entire cob.

$A$ 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 greater lateral surface area and by how much (in $, cm^2$)?

The diameter of the moon is approximately one-fourth of the diameter of the earth. What fraction of the volume of the earth is the volume of the moon?

Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden box covered with coloured paper with a picture of Santa Claus on it (see figure). She must know the exact quantity of paper to buy for this purpose. If the box has length,breadth,and height as $80 \, cm$,$40 \, cm$,and $20 \, cm$ respectively,how many square sheets of paper of side $40 \, cm$ would she require?

$A$ hemispherical bowl is made of steel,$0.25 \, cm$ thick. The inner radius of the bowl is $5 \, cm$. Find the outer curved surface area of the bowl. (in $, cm^2$)

$A$ capsule of medicine is in the shape of a sphere of diameter $3.5 \, mm$. How much medicine (in $mm^3$) is needed to fill this capsule (in $, mm^3$)?