<p>How do you calculate the quartiles? Stats seems to vary a lot from what I studied in the Indian Secondary Certificate course 
Like the variance thing. I heard AP uses /n-1 instead of /n
I’m so confused.
Also, can someone tell wether the following guides are reliable?(I have no hard books to study AP, so need to take free online prep)-
[AP</a> Statistics Tutorial: Graphical Display of Data](<a href=“Data Patterns in Statistics”>Data Patterns in Statistics)
[Holloman’s</a> AP Statistics | Notes](<a href=“http://www.mrholloman.net/APS/Notes/index.htm]Holloman’s”>http://www.mrholloman.net/APS/Notes/index.htm)
[AP</a> Statistics Notes Ms](<a href=“http://www.henry.k12.ga.us/UGH/apstat/chapternotes/index.html]AP”>http://www.henry.k12.ga.us/UGH/apstat/chapternotes/index.html)
[Table</a> of Contents](<a href=“http://arnoldkling.com/apstats/index.html]Table”>Table of Contents)</p>
<p>Thanks!</p>