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Graphical Representation of Data

Graphical representation is another way of presenting data and information. The graphical
representation offers a quick and simple way of understanding and drawing a meaningful
conclusion. In graphical representation, we can represent the data using various kinds of graphs

or charts such as pictographs, bar graphs, histograms, pie charts, line graphs, etc.
In the previous class, we have studied about the pictographs and bar graphs in detail. In this
chapter, we will revisit these concepts and explore single and double bar graphs.

Bar Graph

In bar graphs, bars of uniform width can be drawn horizontally or vertically with equal spacing
between them. The length of each bar indicates the value of the data it represents.
Interpretation of a Bar Graph

Let us consider an example. Adjoining bar graph shows the number of students in a particular class
of a school over different years. Answer the following questions: 1 unit = 10 students
(a) How many total students are there in 2021 to 2024? 70

(b) In which years, the number of students are equal in the class? 60

The answer of the above problem are as follows: 50
40
(a) Number of students in the class in the year 2021 = 60 Number of students 30
Number of students in the class in the year 2022 = 40 20
10
Number of students in the class in the year 2023 = 70
0 2021 2022 2023 2024
Number of students in the class in the year 2024 = 60 Years
Clearly, total number of students in the class from 2021 to 2024

= 60 + 40 + 70 + 60 = 230.
(b) Number of students in the class in the year 2021 = 60
Number of students in the class in the year 2024 = 60
Clearly, the number of students in the year 2021 and 2024 are equal in the class.
Construction of Bar Graph

To construct a bar graph, first, we draw a horizontal line and a vertical line that are mutually
perpendicular to each other. The horizontal line is called the x-axis, and the vertical line is called
the y-axis. On the horizontal line (x-axis), we draw bars and on vertical line (y-axis), we write
numerals that represent the height of the bars. We choose a suitable scale to decide height or
length of the bars.

For example, 1 unit length to represent 1 student only.

Note: (i) The width of the bars should be same throughout.
(ii) The gap between the bars should be equal throughout.

(iii) Choose the scale carefully for determining the height or the length of the bars.

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