1. Introduction to Graphs

Introduction to Graphs

Introduction to graphs

We can represent the same data in terms of graphs. Graphs enhance the ease of understandability and present the data in a simpler form, making the data analysis more comfortable.

Bar graphs

Bar graphs make use of horizontal or vertical columns to represent data.

Double bar graphs are used to denote comparison between two entities


Pie-graphs or circle-graphs represent the whole of data in a circular form. This graph acquired its name from the famous food 'American pie'.


Histograms are similar to bar graphs but are used to represent data for a continuous range of numbers.

line graphs

Line graphs are otherwise called frequency polygons. Similar to histograms, it represents data for a continuous range of numbers. It is mainly used to describe data happening continuously over a period of time.

Introduction to linear graphs

Location of a point

Let us look at a point on the graph sheet and discuss how it is located.

The point A is located 4 units from the x-axis and 3 units from the y-axis. Here, (4, 3) is also known as x and y coordinates.

Coordinates: Coordinates are used to locate the position of a point on the graph easily. They are expressed as x coordinates and y coordinates.

x coordinate = Distance of the point from the y-axis

y coordinate = Distance of the point from the x-axis

While expressing co-ordinates of a point, the x coordinate is always written first, followed by the y coordinate.

Linear graph

When a straight line could join the graph's points, then it is a linear graph.

Here, we can join the points A, B, C, and D to form a straight line. Hence, the points form a linear graph.

In other words, in a line graph, the points are joined using bits of line segments. A line graph does not form a straight line. Whereas in a linear graph, the points on the graph join to form a straight line.

Some applications using graphs 

Independent variable: An independent variable does get affected by the other variable. It can take the values freely. 

Dependent variable: The value of the dependent variable depends upon the independent variable.


In the situations discussed earlier, let us find the independent and dependent variables. 

1. The area of the square depends upon the varying lengths of its side. Hence, the square's side is the independent variable, and the square's area is the dependent variable.

2. The increase in the final amount depends upon the number of books bought. Therefore, the number of books purchased is the independent variable, and the final bill amount is the dependent variable.

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