Answer:
Option B
Explanation:
Volume of sphere = $\frac{4}{3}\pi r^{3}$
Volume of 3 small spherical balls=$\frac{4}{3} \pi (1^{3}+2^{3}+3^{3}$
=$\frac{4}{3}\pi (1+8+27)$$=\frac{4}{3}\pi \times 36$ $=48\pi$
Material loss =25%
$\therefore$ Volume of the single spherical ball $=\frac{48\pi \times 75}{100}$
$\Rightarrow \frac{48\pi \times 3}{4}= 36\pi$
$=\frac{4}{3}\pi r^{3}=36\pi$
$\Rightarrow r^{3}=\frac{36\times 3}{4}=27$ $r=3 cm$
