Temperature has a great affects on the concentration of dissolved oxygen in a pond because temperature is responsible for the presence of high amount of dissolved oxygen in water. At low temperature such as in winter season, the amount of dissolved oxygen in water is higher while in warm temperature such as in summer season, the concentration of dissolved oxygen is lower. So for measuring the mean dissolved oxygen of the cold pond, you have to add the data and then divided by 3, you will get the average dissolved oxygen of the cold pond.
