A wastewater sample has an initial DO of 7.3 mg/L After incubation at <img alt="20^{\circ} \mathrm{C}" src="https://entrancecorner.oncodecogs.com/gif.latex?20%5E%7B%5Ccirc%7D%2
A wastewater sample has an initial DO of 7.3 mg/L After incubation at for 5 days, the DO was reduced to 3.9 mg/L. What is the percentage BOD of the sample?