How many spherical lead shots each …

Let n spherical shots can be obtained
diameter  of spherical shots  = 4.2 cm
{tex}\Rightarrow{/tex} radius of spherical shots  = 2.1 cm

It is given that
length of cuboid  = 66 cm
breadth of cuboid  = 42 cm
height of cuboid  = 21 cm

Spherical lead shots are recasted from cuboid of lead.
So, volume of n spherical lead shots is equal to volume of cuboid.
{tex}\therefore{/tex} Volume of n spherical lead shots = Volume of lead cuboid
{tex}\Rightarrow{/tex} {tex}n \times \frac { 4 } { 3 } \pi r ^ { 3 } = l \times b \times h{/tex} 
{tex}\Rightarrow{/tex} {tex}n \times \frac { 4 } { 3 } \times \frac { 22 } { 7 } \times 2.1 \times 2.1 \times 2.1{/tex} = 66 {tex}\times{/tex} 42 {tex}\times{/tex} 21
{tex}\Rightarrow{/tex} n = {tex}\frac { 66 \times 42 \times 21 \times 3 \times 7 \times 1000 } { 4 \times 22 \times 21 \times 21 \times 21 }{/tex} 
{tex}\Rightarrow{/tex} n = 3 {tex}\times{/tex} 500 = 1500
Hence, the number of lead shots are = 1500.