Finding median of both lower and upper half of the data
Finding the difference between the medians of both lower and upper half of the data.
From the histogram steps involved are
From the cumulative frequency histogram polygon, find the upper quartile which is 3/4* highest column value
locate value in step on in the c.f column on the y-axis
after locating the value on the c.f column, draw a horizontal line from that point to hit the polygon and draw a vertical line all the way down to hit x-axis, this is the upper quartile (Q3) value
Repeat the procedure for lower quartile using 1/4*the highest column value.
The range is obtained by finding the difference between upper quartile, Q3 and lower quartile Q1
From the box plot, the steps for finding interquartile range are;
Find Q1 which is represented on a box plot by the left-hand edge of the box.(where the whisker stops)
Find Q3 which is represented on a box plot by the right hand edge of the box
Find the difference ,Q3-Q1, to get the interquartile range
