The interquartile range gives the middle half of a dataset. It is obtained by subtractionng the value of the lower quartile (Q1) from the value of the upper quartile(3rd quartile).
Interquartile range (IQR) = Q3 - Q1
WHERE ;
Q3 = 3/4 * (n+1)th term and the first quartile (Q1) is given as ;