To find the number of electrons transferred, we should divide the total charge acquired by the rod [tex]Q=-4.9 \mu C=-4.9 \cdot 10^{-6}C[/tex] by the charge of a single electron ([tex]e=-1.6 \cdot 10^{-19}C[/tex]), and we find:
[tex]N= \frac{Q}{e}= \frac{-4.9 \cdot 10^{-6}C}{-1.6 \cdot 10^{-19}C} =3.1 \cdot 10^{13}[/tex]