The diameter of a solid hemisphere is $42\, cm.$ Find the curved surface area of a hemisphere (in $cm^2$).

The capacity of a cuboidal water tank is $60,000$ litres. If its length is $5$ m and breadth is $4$ m, find its height in meters.

$A$ cube of side $4 \, cm$ contains a sphere touching its sides. Find the volume of the gap in between. (in $, cm^3$)

State whether the following statement is true or false:
An open box measuring $12\, cm \times 4\, cm \times 3\, cm$ can hold a bar of $15\, cm$ in length.

The inner diameter of a circular well is $3.5 \, m$. It is $10 \, m$ deep. Find its inner curved surface area. [Assume $\pi = \frac{22}{7}$] (in $, m^2$)

At a Ramzan Mela,a stall keeper in one of the food stalls has a large cylindrical vessel of base radius $15 \, cm$ filled up to a height of $32 \, cm$ with orange juice. The juice is filled in small cylindrical glasses (see figure) of radius $3 \, cm$ up to a height of $8 \, cm$,and sold for $Rs. 15$ each. How much money does the stall keeper receive by selling the juice completely?