1) The graph is linear, because it has an upwards slope of 5, we can tell because 3*5 =15 and 6*5=30.
2)Real world meaning is the delta change. Hence in this case it's the increase in rain over time. More rain or raining harder as time progresses.
3)It is not linear because the second sample shows a slope of 7.5 meanwhile the third sample shows a slope of 6 which allows us to conclude that it is not linear.
4)The y intercept means the total rain that was present at the start of the recording which essentially means there was no rain when she started the experiment.
