Question

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

Section A		Section B
Marks	Frequency	Marks	Frequency
0 - 10	3	0 - 10	5
10 - 20	9	10 - 20	19
20 - 30	17	20 - 30	15
30 - 40	12	30 - 40	10
40 - 50	9	40 - 50	1

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.

Answer 1

We can find the class marks of the given class intervals by using the following formula.

Class mark = `"Upper class limit + Lower class limit"/2`

Section A			Section B
Marks	Class-marks	Frequency	Marks	Class-marks	Frequency
0 - 10	5	3	0 - 10	5	5
10 - 20	15	9	10 - 20	15	19
20 - 30	25	17	20 - 30	25	15
30 - 40	35	12	30 - 40	35	10
40 - 50	45	9	40 - 50	45	1

Taking class marks on the x-axis and frequency on the y-axis and choosing an appropriate scale (1 unit = 3 for the y-axis), the frequency polygon can be drawn as follows:

It can be observed that the performance of students of section ‘A’ is better than the students of section ‘B’ in terms of good marks.