The mass of newborn baby in one day can be calculated as,
[tex]\begin{gathered} m=(1.6\text{ mg/min})(\frac{1\text{ kg}}{10^6\text{ g}})(\frac{60\text{ min}}{1\text{ h}})(\frac{24\text{ h}}{1\text{ day}}) \\ =0.002304kg.day^{-1} \end{gathered}[/tex]The time taken by brain's mass to increase can be calculated as,
[tex]\begin{gathered} t=\frac{0.0075\text{ kg}}{0.002304\text{ kg/day}} \\ =3.25\text{ days} \end{gathered}[/tex]Thus, the time taken by bran's mass to increase is 3.25 days.
