Bar Graphs

• Bar graph is the graphical representation of the set of data.
• It is rectangular bar of equal width and the height of the bar is proportional to the value of data they represent.
• It has two lines, one horizontal line and one vertical line.
• The horizontal line represents the data type or the data categories.
• The vertical line represents the data value.

The graph below shows a bar graph of the number of food items that were sold in the shop.

Properties of Bar graphs

• All the bar must be equally spaced.
• The height of the bar represents the data value.
• The bar graphs must have a title, labels and scales.
• The data value must always start with 0.

Types of Bar graphs

• Horizontal bar graph
• Vertical bar graph

Horizontal Bar Graphs

• The data are arranged horizontally.
• In this graph the data type is in the vertical line and the data value is in the horizontal line.
• The bar runs from left to right.

Vertical Bar graphs

• The data are arranged vertically.
• In this graph the data type is in the horizontal line and the data value is in the vertical line.
• The bar runs from down to up.

Steps to draw Vertical Bar graphs

Interpret the Bar Graphs

• The title of the bar graph tells us what the data is about.
• The horizontal lines and the vertical lines represent the data type and the data value respectively.
• The horizontal bar graph below shows the graph of the favorite fruits of the group of students.

From the graph it can be visualized that:

• The bar representing the mango is the longest bar.

Therefore, most of the students like Mango.

• The representing the orange is the shortest bar. Therefore, the least liked fruit is Orange.
• The scale of the graph is: 1 unit = 5 students.
• 10 students liked Apple.
• 20 students liked Mango.
• 5 students liked Orange.
• 15 students like Banana.

Example:

Given below is the data of the number of students with their pets.

Draw a vertical bar that represents the given information and answer the following question:

1. Which pet is kept by the maximum number of students?
2. Which pet is kept by least number of students?

Solution:

The vertical bar graph is:

1. The graph shows that the maximum number of students liked cats.
2. The graph shows that the minimum students liked rabbits.