Hi

I was given an assignment and there is one question that is killing me. it goes as follows:

Consider the following data from a BOD test:
Days. DO(mg/l)
0... 9
1... 9
2... 9
3... 8
4... 7
5... 6
10... 6
15... 4
20... 3
25... 3

The very first question is what is BOD5.

I cannot seem to find anything relating to how to calculate the answer without a sample volume (assuming volume of container is 300ml)

is there anyone out there who can lead me to the correct direction please??