For point 3, you could take the result volume after one minute/ reaction time (1 minute) this result will be pretty forward. Nonetheless it wil change with the next row, volume after two minutes/ reaction time (two minutes). For point 4, you have to average the results you got in point 3 for each row. I see you have got the average for column "after one minute", but the result will be different in the average of column "after two minutes". Perhaps you could update a column, that could have this title "volume after two minutes/two", there you could put the results of such division. The average of the results of that column will complete the answer for point 4.