Line Plot

A line plot is also known as a dot plot. In the line plot, data is represented on a number line using symbols for frequency.

Step by step guide to the line plot

A line plot is a graphical representation of data in a line of numbers using a dot, a cross, or any other symbol. Each symbol indicates a specific quantity, which is the scale of the chart. The categories of the data are displayed on the number line followed by drawing marks or symbols to indicate the variables over each category.

Line plot graph

A line plot graph is a way to graphically display the data on a number line using symbols. It is different from a line graph because we are not using a Cartesian plane or an \(x\) and \(y\)-axis to display data. A line plot graph is drawn simply on a number line.

For example, in a survey of favorite sports with \(12\) children, it was found that \(5\) children like cricket, \(3\) children football, \(1\) child volleyball, and \(3\) children badminton. This data can be displayed in a line graph as follows:

The number line indicates the name of the sport and the \(x\) symbol indicates the number of children.

How to make a line plot?

A line plot is a good way to display data graphically. Follow the steps below to create a line plot:

• Step 1: Identify the data category. In the example above, there were \(4\) categories in which the data was collected: cricket, football, volleyball, and badminton.
• Step 2: Count the frequency of each category and display it using any symbol you choose. For example, if \(5\) kids like cricket, we draw 5 symbols \((x)\) above Cricket. However, it is important to use only one type of symbol along with the chart. For example, we do not use the dot and the cross sign together in one line plot to represent the same thing.
• Step 3: Mention the label and scale. The label is what we write under the categories on the number line. For example, in the above graph, “Favorite Sport” is the label. A scale is a unit or number that each symbol represents. In the above chart, the scale is “\(1 x = 1\) child”.

However, when we use \(1\) unit as a scale, in many places you may find that the scale is not used. Therefore, when the scale is not mentioned, we consider it as \(1\) unit.

Reading a line plot

To read a line plot, we must first identify the scale or units that each symbol represents. If nothing is mentioned, we consider it \(1\) unit. Then we count the symbols used in each category in the number line. Multiply the number of symbols by the scale to get the frequency of each category.

Line plot with fractions

A line plot with fractions is made like other numbers or variables. In this, we show the fractional values on the number line, and their frequencies or the number of times they are occurring in the data set above each fraction.

Take a look at an example of a line plot with fractions given below showing the number of hours spent on reading books by \(21\) people in a library.

By reading this line plot, we can interpret that \(3\) people spent \(\frac{3}{4}th\) hour in reading, \(4\) people spent \(1\) hour in reading, and so on.

Line Plot – Example 1:

See the line plot below, which shows the number of bikes sold by \(XYZ\) makers \(7\) days a week.

How many bicycles did they sell Monday and Wednesday together?

Solution:

In the given line plot, each dot is representing \(10\) bikes. It means \(1\) dot \(= 10\) bikes.

Number of bikes sold on Monday \(= 4 × 10 = 40\) bikes

Number of bikes sold on Wednesday \(= 5 × 10 = 50\) bikes

Total bikes sold on both days \(= 40 + 50 = 90\) bikes

Exercises for Line Plot

1. John asks all his friends how many times a week they play video games. Each \(x\) in the line plot represents a friend. How many of John’s friends said they play video games more than twice a week?

2. Class sizes in middle school range from twenty-five to thirty-five students. The line plot below shows the number of sixth-graders in each class. What is the mode, or most common, number of students per class?

1. \(\color{blue}{Ten\:friends}\)
2. \(\color{blue}{29\:students}\)