Mathematics
Grade 8
15 min
Interpret line plots
Interpret line plots
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1
Introduction & Learning Objectives
Learning Objectives
Identify and describe the components of a line plot, including the number line and data points.
Determine the frequency of specific data values from a line plot.
Calculate measures of center (mean, median, and mode) from data presented in a line plot.
Calculate measures of spread (range) from data presented in a line plot.
Describe the overall shape, clusters, gaps, and outliers of a data set displayed on a line plot.
Draw conclusions and make inferences about a data set based on its line plot representation.
Ever wonder how many hours your classmates spend on homework? 📚 Or how many pets they have? 🐾 Line plots help us quickly see and understand this kind of data!
In this lesson, you'll learn how to read and understand line plots, which are simpl...
2
Key Concepts & Vocabulary
TermDefinitionExample
Line Plot (Dot Plot)A graph that displays data using a number line and X's or dots to show the frequency of each value. Each 'X' or dot represents one data point.A line plot showing the number of pets students own might have 3 'X's above the number '2', meaning 3 students own 2 pets.
Data PointEach individual piece of data recorded on the line plot. On a line plot, each 'X' or dot represents one data point.If a line plot shows the number of hours students spent reading, each 'X' above '3' hours represents one student who read for 3 hours.
FrequencyThe number of times a particular data value occurs. On a line plot, it's indicated by the number of X's or dots stacked above that value on the numb...
3
Core Formulas
Calculating the Mean from a Line Plot
$\text{Mean} = \frac{\text{Sum of all data values}}{\text{Number of data values}}$
To find the mean, multiply each data value by its frequency, sum these products, and then divide by the total number of data points (total frequency).
Finding the Median from a Line Plot
Order all data values from least to greatest. The median is the middle value. If there are two middle values (an even number of data points), the median is their average.
List out each data point individually based on its frequency. Then, find the value that is exactly in the middle of this ordered list.
Identifying the Mode from a Line Plot
The mode is the data value(s) that appear most frequently (have the most X's or dots) on the line plot.
Look for the val...
5 more steps in this tutorial
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Challenging
The line plot shows the number of siblings for students in a class.
Number of Siblings
X
X X
X X X
X X X X
--|---|---|---|---|---
0 1 2 3 4
If a new student with 4 siblings joins the class, how will the mean and median of the data set be affected?
A.Both the mean and median will increase.
B.The mean will increase, but the median will stay the same.
C.The mean will stay the same, but the median will increase.
D.Both the mean and median will decrease.
Easy
On a line plot, what does each individual 'X' or dot placed above a number on the number line represent?
A.The average of the entire data set
B.single data point
C.label for a category
D.The frequency of all values
Easy
A line plot shows the results of a class quiz. There are 3 X's above the number 8. What is the frequency of the score 8?
A.3
B.8
C.11
D.Cannot be determined
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