The mean is simply the average of all the stats combined.
The amount of fireworks are usually the most in the beginning of July (July 4th to be specific). Since the question asks for the whole month of July, using the mean or average won't be as accurate because the average accounts for the WHOLE month. There will be a lot of fireworks used in the beginning of the month but that will dwindle to almost none after the first week if that makes sense.
