A 10 mL sample is added to a 300 mL BOD bottle. Dilution water is added to the sample bottle and the initial dissolved-oxygen concentration is measured as 8.5 mg/L. After the sample is sealed, the laboratory incorrectly takes a measurement of dissolved-oxygen reading on day 6 of 3 mg/L. If the BOD reaction rate coefficient for the sample is 0.30/day,

(a) estimate what the BOD5 should have been.

(b) Estimate what the dissolved-oxygen reading should have been on day 5.

(c) Determine the BOD _u of this sample.