$A$ metallic sphere with diameter $12 \, cm$ is melted and identical balls with radius $0.3 \, cm$ are produced. Find the number of balls produced.

Water flows through a cylindrical pipe,whose inner radius is $1 \,cm$,at the rate of $80 \,cm/sec$ into an empty cylindrical tank,the radius of whose base is $40 \,cm$. What is the rise of water level in the tank in half an hour? (in $cm$)

The base of a cone with radius $15\, cm$ and slant height $25\, cm$ is hemispherical. Find the volume of this solid. $(\pi=3.14)$ (in $cm^{3}$)

Water flows at the rate of $10 \, m/min$ through a cylindrical pipe $5 \, mm$ in diameter. How long would it take to fill a conical vessel whose diameter at the base is $40 \, cm$ and depth $24 \, cm$?

$A$ well of diameter $3 \, m$ is dug $14 \, m$ deep. The earth taken out of it has been spread evenly all around it in the shape of a circular ring of width $4 \, m$ to form an embankment. Find the height of the embankment (in $m$). Take $\pi = \frac{22}{7}$.

$A$ cistern,internally measuring $150 \,cm \times 120 \,cm \times 110 \,cm$,has $129600 \,cm^3$ of water in it. Porous bricks are placed in the water until the cistern is full to the brim. Each brick absorbs one-seventeenth of its own volume of water. How many bricks can be put in without overflowing the water,each brick being $22.5 \,cm \times 7.5 \,cm \times 6.5 \,cm$?