Page 1 - Lesson note-3-Ch 14 Statistics Graphical Representation

SAI International Residential School
Class –IX

Mathematics

Chapter-14: Statistics

Sub topics: Graphical Representation of Data, Bar Graphs, Histogram

LESSON NOTES-3

Graphical Representation of Data
Graphical Representation is a way of analysing numerical data. It exhibits the relation
between data, ideas, information and concepts in a diagram.

We shall study the following graphical representations in this section.
(A) Bar graphs
(B) Histograms of uniform width, and of varying widths
(C) Frequency polygons
Representation
Merits of Using Graphs
Some of the merits of using graphs are as follows:

• The graph is easily understood by everyone without any prior knowledge.
• It saves time.
• It allows to relate and compare the data for different time periods.
• It is used in statistics to determine the mean, median and mode for different data,
as well as in interpolation and extrapolation of data.

Bar graph

A bar graph is a pictorial representation of data in which usually bars of uniform
width are drawn with equal spacing between them on one axis (say, the x-axis),
depicting the variable. The values of the variable are shown on the other axis
(say, the y-axis) and the heights of the bars depend on the values of the variable.