CBSE Notes Class 8 Maths Chapter 13 Introduction To Graphs

1.0Introduction 

The graphs are the visual representation of collected data. In Maths, the purpose of the graph is to show numerical data in visual form so that they can be understood clearly, quickly, and easily. This data can also be collected in the form of a table, but the visual representation is much more interesting and easy to understand. Here is what graph-represented data looks like. 

2.0CBSE Class 8 Maths Chapter-13 Introduction to Graph - Revision Notes

Some Important Terms

• Data: The data is the information that can be collected and represented in a graph. 
• Coordinates: Coordinates are the pair of values (X, Y) that indicate a point on the graph. 
• X-axis: It is the horizontal line in the graph. In maths, it usually represents time or category. 
• Y-axis: It is the vertical line in the graph that typically represents quantity or value. 
• Line Graph: It is the graph that represents a line connected by points to show a given data. 

3.0Line Graph

In maths, a line graph is a graph where individual data points are connected by straight lines. It is the most often used graph showing trends over time.

• Typically, the X-axis represents time, such as days, months, etc.
• The y-axis would include values (such as temperature or sales, etc.).

Purpose: Line graphs are used to show how something changes over time; they help us spot patterns such as increasing, decreasing, or levelling in data. 

Below is the figure showing a line graph. 

Let’s try to answer some questions related to the above graph.

Q1: What are the bedtime hours of the person on Friday? 

Answer: 4.0 hours.

Q2: What information is given on both the axes? 

Answer: On the X-axis, the days of the week are shown. And hours of bedtime are shown on the Y-axis.

Q3: On which day the no. The hours of bedtime is the least?

Answer: On Saturday.

Q4: On which day the no. The hours of bedtime is the most? 

Answer: Friday. 

How to Draw a Line Graph in Maths

1. Draw the axes: Draw both the X-axis (Horizontal axis) and the Y-axis (Vertical axis). 
2. Label the axes: Label the axis according to the data. Assign each axis to the given data in the above graph. 

• The X-axis is given the name of the day, month, or other data most often. 
• The Y-axis is given the numerical data for most of the time. 

3. Choose the Scale: choose the scale according to the given data for the Y-axis. 
4. Plot the points: Plot the points first so that you do not make any mistakes. 
5. Connect the points: Connect the points using a scale to form a line or lines. 
6. Title: Give the graph an appropriate title according to the data given. 

4.0Solved Problems 

Problem 1: The table below shows the number of books in red for the months of the year. 

Draw a line graph for the following table. 

Problem 2: 

Population (in thousands) of men and women in a village in different years.

5.0Key Features of CBSE Maths Notes of Class 8 Chapter 13

• The notes are aligned with the latest CBSE curriculum. 
• Visual aid is provided with every concept related to Graphs to make it easy to understand. 
• A Step-by-Step guide along with solved examples are provided for a clear understanding of the concepts. 
• The notes also provide FAQs to give an idea of some rare facts related to graphs.