Represent and Interpret data

Key Concepts

• Data and line plot
• Reading the line plot
• Analyzing the line plot

Introduction

In this chapter, we will learn about data and line plots, how to read the line plot and how to analyze the line plot. 

Data and line plot 

What are line plots? 

A line plot is a way to display data along a number line. 

Line plots are also called dot plots. 

Example 1: 

17 turtles were walking on the beach. They walked for one hour, and each turtle covered a certain distance. The below table shows the distances covered by each turtle in meters. 

Let us draw the line plot for the above data. 

Step 1: Sort the data from the least to the greatest. 

20, 21, 23, 24, 25, 26, 27 

Step 2: Draw the number line. 

Step 3: Arrange the data in a table. 

Step 4: Plot the values in the number line. 

Draw 3 dots above 21 because 3 turtles travelled a distance of 21 meters in an hour. 

Step 5: Draw 0 dots above 22 because 0 turtles travelled a distance of 22 meters in an hour.         

Similarly, draw dots for other values. 

Example 2:   

A class has 21 students. The following data represents the number of pets each student has. 

Step 1: Sort the data from the least to the greatest. 

0, 1, 2, 3, 4, 5, 6 

Step 2: Draw the number line. 

Step 3: Arrange the data in a table. 

Step 4: Plot the values in the number line. 

Reading line plots 

Example 1:  

The below line plot shows the number of new necklaces made by 5 friends. 

What do you understand from this line plot? 

Solution: 

The five friends made new necklaces of lengths 51, 52, and 54 centimetres. 

Analyzing the line plot 

Example 1: 

Five friends made new necklaces of the lengths 52, 51, 52, 54, and 52 centimetres. 

1. How many necklaces were 51 cm long? 

2. How many necklaces were 52 cm long? 

3. How many necklaces were 54 cm long? 

4. Which length of the necklace was made by the maximum friends? 

Solution: 

By observing the above line plot, we can understand the below points, 

1. 1 necklace was 51 cm long. 

2. 3 necklaces were 52 cm long. 

3. One necklace was 54 cm long. 

4.  Maximum friends made a 52 cm necklace. 

Example 2:  

The below line plot represents the number of hours spent on reading. 

1. How many students spent one hour reading? 

a. 3 students 

2. How many students spent three hours reading? 

a. 4 students 

3. How many students spent more time reading? 

a. 5 students  

Exercise

1. The heights of Sabrina’s dolls are shown below. How many dolls are taller than 22 centimetres?

2. A park ranger counted stripes on each baby zebra. She is going to make a line plot of the data. Graph the measurements from the table on the line plot.

3. Suppose you count the number of students in each classroom in your school.

Draw a line plot for given data.

4. Mr Haley’s class created this line plot to show how many candy bars each student likes. How many students like three candy bars?

5. How many cars were sold in all?

6. Answer the below question using the following line plot. Each X represents one student.

Find the total number of hours spent on reading by the students.

7. The teacher wrote down how many pictures frame the students made last week. How many children made fewer than 2 picture frames?

8. Mr Jensen recorded the scores on a math quiz. How many students scored more than 7?

9. Some people took photos while visiting the zoo. How many people took at least 1 photograph?

10. Some children compared how many thank-you notes they wrote last month. How many children are there in all?

Concept Map 

What have we learned

• Understanding data and line plots
• How to arrange the data on a line plot
• How to read the line plots
• Understanding and analyzing the line plots
• Generating a graph based on the ordered pairs