Hydrologic Cycle, Precipitation & Unit Hydrographs question bank (Water Resources & Environmental Engineering)

A wastewater sample has an initial dissolved oxygen (DO) of $9.0\text{ mg/L}$. After 5 days of incubation at $20°\text{C}$ in a $300\text{ mL}$ standard BOD bottle with $5\text{ mL}$ wastewater sample and remaining dilution water (dilution blank DO drop = $0$), the final DO is $3.0\text{ mg/L}$. What is the $\text{BOD}_5$ of the wastewater?

[Hydrologic Cycle, Precipitation & Unit Hydrographs Concept 6] A wastewater sample has an initial dissolved oxygen (DO) of $9.0\text{ mg/L}$. After 5 days of incubation at $20°\text{C}$ in a $300\text{ mL}$ standard BOD bottle with $5\text{ mL}$ wastewater sample and remaining dilution water (dilution blank DO drop = $0$), the final DO is $3.0\text{ mg/L}$. What is the $\text{BOD}_5$ of the wastewater?