The frequency distribution is given below:

Marks	$0-20$	$20-40$	$40-60$	$60-100$
Number of Students	$10$	$15$	$20$	$25$

This distribution has been represented graphically as shown in the image. Is this representation correct? Explain.

(N/A) The given graphical representation is incorrect.
In a histogram,the area of each rectangle is proportional to the frequency of the corresponding class interval. When class intervals are of unequal width,the heights of the rectangles must be adjusted to be proportional to the frequency density,which is defined as $\frac{\text{Frequency}}{\text{Width of class interval}}$.
Here,the class widths are:
$0-20$: width $= 20$
$20-40$: width $= 20$
$40-60$: width $= 20$
$60-100$: width $= 40$
Since the last interval $(60-100)$ has a different width,the height of the rectangle for this interval should have been adjusted to maintain the area proportionality. The current graph simply plots frequency against class intervals,which is only valid for equal class widths.