$A$ river $3 \,m$ deep and $40 \,m$ wide is flowing at the rate of $2 \,km$ per hour. How much water will fall into the sea in a minute (in $,m^3$)?

The curved surface area of a cylinder is $3960\, cm^{2}$. If its radius is $21\, cm$,find its height in $cm$.

The volume of a solid cylinder is $4620 \, cm^{3}$ and its radius is $7 \, cm$. Find its height in $cm$.

Write True or False and justify your answer.
$A$ right circular cylinder just encloses a sphere of radius $r$ as shown in the figure. The surface area of the sphere is equal to the curved surface area of the cylinder.

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?

The length, breadth, and height of a cuboid are $30 \, cm$, $20 \, cm$, and $15 \, cm$ respectively. Its volume is $\ldots \ldots \ldots \, cm^3$.