How do I do Qn2.3 to get the answer provided?

2.3 Figure 2 shows the changes of BOD remaining for a wastewater sample with time. The BOD experiment was conducted under standard conditions. 55 50 45 40 35 30 BOD Remaining (mg/L) 25 20 15 10 5 0 0 5 10 15 20 25 30 Time (day) Figure 2: BOD remaining-time profile for wastewater sample. (a) State the temperature of the experiment that was conducted. (1 mark) (b) Find the BODs and BODL of the wastewater sample. (4 marks) (c) Determine the sample's BOD rate constant. (2 marks) (d) Calculate the maximum dilution factor for the wastewater sample such that the dissolved oxygen (DO) of the diluted sample would not drop below 1.0 mg/L at the end of the five-day measurement period. Assume the DO of the diluted sample at the start was 8.5 mg/L. (3 marks) 2.3(a) T = 20C 2.3(b) BODs = 40 mg/L BODL = 50 mg/L 2.3(c) k25 = 0.140 day! 2.3(d) Dilution factor = 5.3