Final answer:
Without a clear description or visual representation of the number line and the blue dot's location, it's impossible to determine the blue dot's position among the options -3.15, -3.2, and -3.25.
Step-by-step explanation:
The original question seems to contain several unrelated parts that are intended to provide a number line context, but they do not clearly correspond to the blue dot's position. Based on the provided parts of the question, we cannot determine where the blue dot is on the number line when the options given are -3.15, -3.2, and -3.25. To find the blue dot's position, the number line and the blue dot's specific location relative to known values on that line would need to be clearly described or visually provided.