An industry discharges $2$ million liters per day $\text{(MLD)}$ of wastewater with a temperature of $45^{\circ} \mathrm{C}$ and a $\mathrm{pH}$ of $2$, whereas the neighboring industry produces $3 \mathrm{MLD}$ of wastewater with a temperature of $30^{\circ} \mathrm{C}$ and $\mathrm{pH}$ of $8$. If both the wastewaters are mixed and carried through a pipeline, then the resultant $\mathrm{pH}$ of mixed wastewater is _________ $\text{(rounded off to $2$ decimal places)}$.
Neglect buffering capacity of the system and the temperature effect on $\mathrm{pH}$.
