For calculating the mode of the grouped data graphically, the following procedure is adopted.
Draw a histogram of the data; the modal class is the tallest rectangle.
Draw a line from the top right corner of the tallest rectangle to the top right corner of the preceding rectangle.
Draw a line from the top left corner of the tallest rectangle to the top left corner of the succeeding rectangle.
Draw a line perpendicular to the X-axis from the point of intersection of lines drawn in steps 2 and 3. The point of intersection of the perpendicular line with the X-axis represents the mode.
Let us calculate the Mode using the graphical method for the following distributions:
Gross profits as percentage of sales
Number of companies
Using the procedure described above, we draw the histogram and other lines for the calculation of mode. The mode is 25.