Quartiles

Quartiles
I.	Finding Q1
A.	.25(n)
Example:  .25(18)= 4.5, round up, value of 5th data point.  
II.    Finding Q3
 A.	.75 (n)
Example:  .75(18)=  13.5, Round up, value of 14th data point.  
III.	  Interquartile Range(IQR) Q3-Q1
          Difference between values of 14th and 5th data points. 

      IV.   Checking for Outliers
A.	Q1 -1.5 (IQR)
after computing formula, we get a value of 4;  if we have a 3 in data set, then 3 is an outlier!!
B.	Q3+1.5(IQR)
after computing formula, we get a value of 65;  if we have a 66 in data set, then 66 is an outlier!!