The following table gives the distribution of students of two sections according to the marks obtained by them: 

Represent the marks of the students of both the sections on the same graph by two frequency polygons. From the two polygons compare the performance of the two sections

Without drawing the histogram we can draw the frequency polygon.

for drawing this type of graph we need the midpoints and formula for finding the midpoints for each class is as follows, 

Class mark = Midpoint = $\frac{Upper limit + Lower limit}{2}$

So the midpoint table for both sections is 

and the frequency polygon is ,