Bar Graphs, How to Draw a Bar Graph?

Bar Graphs, How to Draw a Bar Graph?

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.

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. The following example shows the horizontal bar graph.

Solved Examples on Bar Graphs

Example 1: The following table shows birthdays of 40 children in a year.

No. of children

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.

Profits (Rs)

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.

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