How do I know what is the data set when I have the random variable and what does that help when knowing that it distributes as normal distribution.
Say I have concentration of gas the problem says that it distributes normally . In each day at 8:00 morning . In 2018 .
From the problem :
Is my data set : group of days such that in each day concentration ?
Or : group of hours in each hour concentration ?
How can you tell .
What is the relation with normal distribution graph area