The following two tables give the distribution of students of two sections according to the marks obtained by them:

Represent the marks of both the sections on the same graph by two frequency polygons.

Explanation

First we obtain the class marks as shown below.

We represent the class marks along the x-axis on a suitable scale and frequencies along the y-axis on another suitable scale.
To obtain the frequency polygon of section A, we plot the points A(-5, 0), B(5, 3), C(15, 9), D(25, 17), E(35, 12), F(45, 9) and G(55, 0), Now, join these points in pairs successively to obtain the frequency polygon ABCDEFG, as shown below. To obtain the frequency polygon of section B, we plot the points A(-5, 0), P(5, 5), Q(15, 19), R(25, 15), S(35, 10), T(45, 1) and G(55, 0). Now, join these points successively to obtain the frequency polygon APQRSTG, as shown below.