Calculate mode of the following series , using the Graphic Technique :

Explanation

The adjoining graph shows expenditure on the X-axis and number of families on the Y-axis . As is evident , class interval 20-30 corresponds to the highest rectangle in the graph , and is therefore , the modal class intervel.
For the calculation of model value , AD and BC lines are drawn to join the top ends of the model rectangle with the immediate next ends of the adjoining rectangles . these lines are crossing each other at point E. A perpendicular is drawn from point E on the X- axis to locate the exact value of mode which is 24.A counter check of this modal value may be made by calculating mode with the following formula :
`Z=l_(1)+(f_(1)-f_(0))/(2f_(1)-f_(0)-f_(2))xxi`
`=20+(27-23)/(2(27)-23-21)xx10`
`=20+(4)/(54-44)xx10`
`=20+(4)/(10)xx10`
`=20+4=24`
Thus, Mode (Z) =24.