Bar Graphs
A bar graph or bar chart is a graphical representation of numerical data
using bars or rectangles of uniform widths and different heights.
The heights of the bar depend on the number they represent. Bar
graph helps us to draw valid conclusion from it at a glance. Bar graph is also
known as column graph.
How to Draw a Bar Graph?
To draw a bar graph, follow these steps:
1. Draw two mutually perpendicular lines—one horizontal and one vertical on a graph paper.
2. The horizontal line is named x-axis and the vertical line is named y-axis. Their point of
intersection is called the origin.
3. Along the horizontal axis, we represent one of the variables and along the vertical axis, the corresponding data of the other variable is represented.
4. Along the horizontal axis, we choose the convenient and uniform width of bars keeping a uniform gap between them.
5. Choose a suitable scale to determine the height of the bars and then draw vertical bars of equal width.
The following bar graph shows the different types and number of school supplies used by students. The more the height of the bar, the more is the number of the supply or item used.
The following bar graph shows the different types and number of school supplies used by students. The more the height of the bar, the more is the number of the supply or item used.
From the
above bar graph, we can conclude that pencils are supplied the most and pens
are supplied the least.
What is a Bar Graph Used for?
A bar graph or a bar chart is a visual
tool that uses bars to compare data among categories. The important thing to
know is that the longer the bar, the greater its value.
Bar graphs consist of two axes. The horizontal
axis (or x-axis) shows the data categories and the vertical axis (or y-axis) is
the scale.
Bar
graphs have these key properties:
·
A bar diagram makes
it easy to compare sets of data between different groups at a glance.
·
The graph represents
categories on one axis and a discrete value in the other. The goal is to show
the relationship between the two axes.
·
Bar graphs can also
show big changes in data over time.
When to Use a Bar Graph?
Bar chart or graph is an effective way
to compare items between different groups.
Bar charts are an extremely effective
visual to use in presentations and reports. They are popular because they allow
the reader to recognize patterns or trends far more easily than looking at a
table of numerical data.
Types of a Bar Graph
According to the bars represented vertically or horizontally, the bar graphs are of 2 types.1. Vertical Bar Graph
The most common type of bar graph is
the vertical bar graph. In this type of bar graph, the bars are represented
vertically. The following example shows the vertical bar graph.
2. Horizontal Bar Graph
In this type of bar
graph, the bars are represented horizontally.
Solved Examples on Bar Graphs
Example 1:
The
following table shows birthdays of 40 children in a year.
Days
|
Mon
|
Tue
|
Wed
|
Thu
|
Fri
|
Sat
|
Sun
|
No.
of children
|
7
|
3
|
8
|
11
|
3
|
2
|
6
|
Draw the bar graph to represent the above data.
Solution: Draw two lines x-axis and y-axis. Take
days along the x-axis and the number of
children along the y-axis.
Scale: 1 cm = 2 children
Example 2:
The following table shows the daily
profits of four branches of a restaurant.
Branch
|
A
|
B
|
C
|
D
|
Profits
(Rs)
|
32000
|
49000
|
25000
|
38000
|
Represent the above data using a bar graph.
Solution: Draw two lines x-axis and y-axis. Take branches
along the x-axis and the profits
along the y-axis.
