A five$-$day BOD test is performed on an industrial wastewater sample that contains no bacteria; therefore, a "seeded" BOD test is run. $10ml$ of "seed" are added to $20L$ of dilution water. $30ml$ of industrial wastewater are added to a $300ml$ BOD bottle and the remaining volume consists of "seeded" dilution water. The average dissolved oxygen concentration of the diluted wastewater samples and blanks $($seeded dilution water$)$ on the first day of the test is $7\mathrm{.}5m\frac{g}{L}$ and $9\mathrm{.}0m\frac{g}{L},$ respectively. After incubating separate BOD bottles at $20C$ for five days, the average DO concentration of the diluted wastewater BOD bottles and seeded dilution water BOD bottles is $3\mathrm{.}1$ and $8\mathrm{.}5m\frac{g}{L},$ respectively. Use Equation $(3\mathrm{.}13)$ for calculating the five$-$day BOD of the industrial wastewater.