Answer:
Warm air rises, creating a low pressure zone; cool air sinks, creating a high pressure zone.
To get an average, you must add all of the numbers together, and divide that sum by the amount of numbers there are. There are 6 number, which is what we must divide by.

6.8g is the average for the set of measurements.
Oxygen.
Oxygen was fatal when organisms started using photosynthesis, this event was known as the Great Oxidation Event.
Penicillin was made to help soldiers