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Bar Graphs

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Bar Graphs

Have you ever tried to display data in a bar graph? Take a look at this dilemma.

The students in Mr. Hawkins’ class have continued to learn about the Iditarod. After learning some of the basics about the distances covered, the students began to research information about the teams, where they come from and how many teams have entered the race in the past few years. Mr. Hawkins has asked them to create either a bar graph or a line graph of the data that they discover.

Tommy and Keith decided to investigate where the mushers come from. They do some research on the computer and discovered that in 2010, that there were a total of 71 mushers who entered the race. They came from several different states and countries. Tommy and Keith organized their data like this.

46 Mushers from Alaska

13 Mushers from other US states

12 Mushers from other countries

Now they need to put their data into either a bar graph or a line graph.

Yana and Jena have decided to look at how the number of teams has changed over time. They looked at the number of teams that have entered the Iditarod in 2006, 2007, 2008, 2009 and 2010. Here is how they organized their data.

2006 – 83 teams

2007 – 82 teams

2008 – 95 teams

2007 – 67 teams

2006 – 71 teams

Now they need to put their data into either a bar graph.

This Concept will teach you all you need to know about bar graphs. When we are finished, you will be able to help the students put the data into a bar graph.

Guidance

Tables and graphs are ways to organize and present information so that they can be easily interpreted by the viewer. Graphs are created to show the relationship between two variables. For example, a graph may be constructed to depict the relationship between an object’s mass and volume or the price of gasoline in relationship to location.

A bar graph is a graph that uses columns to show the comparison of quantities or amounts. For example, the bar graph below depicts the average price of one gallon of gasoline in five states. Looking at the bar graph, you can conclude that Hawaii has the highest average cost per gallon of gasoline and Missouri has the lowest cost.

This bar graph was completed for you to analyze. Next you can learn how to take a set of data and create your own bar graph.

Thirty students in grade seven were asked to state their favorite after school activity. The results of this survey are shown on the table. Create a bar graph to display the information from the data table.

Favorite Activity: Number of Students:
Watching T.V. 9
Playing sports/exercising 6
Reading 7
Hanging out with friends 5
Babysitting 3

To create a bar graph

1. Draw the horizontal (x) and vertical (y) axis.

2. Give the graph the title “Seventh Grader’s Favorite Activities.”

3. Label the horizontal axis “Favorite Activity.”

4. Label the vertical axis “Number of Students.”

5. Look at the range in data and decide how the units on the vertical axis (y) should be labeled. In this case, since the range in data is not that great, label the vertical axis 0 – 10 by ones.

6. For each activity on the horizontal (x) axis, draw a vertical column to the appropriate value. For example, you will draw a vertical column to the number “9” for the activity “Watching T.V.”

Here is another situation that uses a bar graph.

The data table below depicts the recommended minimum number of hours of sleep people need by age. Create a bar graph using the information from the data table.

Age Group: Recommended Hours of Sleep:
Infants (0–1 years old) 15 hours
Children (2–5 years old) 13 hours
Children (6–11 years old) 11 hours
Teens 9 hours
Adults 8 hours

To create a bar graph:

  1. Draw the horizontal (x) and vertical (y) axis.
  2. Since the graph is about sleep, give the graph the title “Sweet Dreams.”
  3. Label the horizontal axis “Age.”
  4. Label the vertical axis “Hours of Sleep.”
  5. Look at the range in data and decide how the units on the vertical axis (y) should be labeled. In this case, label the vertical axis 0 - 16 by twos.
  6. For each age group on the horizontal (x) axis, draw a vertical column to the appropriate value. For example, for “Infants,” draw a vertical column to fifteen hours.

Looking at bar graphs can help us to make conclusions about the data.

Looking at the bar graph “Sweet Dreams,” what can you infer about age and the recommended number of hours of sleep?

Looking at the graph, you can see that one needs less sleep as they grow older. It is recommended that infants sleep a minimum of fifteen hours a day. However, it is recommended that adults sleep a minimum of eight hours a day. This difference of seven hours is also known as the range.

Take a few minutes and write down the steps to creating a bar graph.

Now look back at the bar graph on recommended hours of sleep and answer the following questions.

Example A

What is the difference between recommended hours of infant sleep and a 2 - 5 year old child's sleep?

Solution: 2 hours

Example B

What is the recommended hours of sleep for an adult?

Solution: 8 hours

Example C

What is the recommended hours of sleep for a teen?

Solution: 9 hours

Here is the original problem once again. Reread it and then look at the graphs created.

The students in Mr. Hawkins’ class have continued to learn about the Iditarod. After learning some of the basics about the distances covered, the students began to research information about the teams, where they come from and how many teams have entered the race in the past few years. Mr. Hawkins has asked them to create either a bar graph or a line graph of the data that they discover.

Tommy and Keith decided to investigate where the mushers come from. They do some research on the computer and discovered that in 2010, that there were a total of 71 mushers who entered the race. They came from several different states and countries. Tommy and Keith organized their data like this.

46 Mushers from Alaska

13 Mushers from other US states

12 Mushers from other countries

Now they need to put their data into either a bar graph or a line graph.

Yana and Jena have decided to look at how the number of teams has changed over time. They looked at the number of teams that have entered the Iditarod in 2006, 2007, 2008, 2009 and 2010. Here is how they organized their data.

2006 – 83 teams

2007 – 82 teams

2008 – 95 teams

2007 – 67 teams

2006 – 71 teams

Now they need to put their data into either a bar graph or a line graph.

Let’s start with the boys. They are looking at the number of mushers from different places. Nothing is changing in their data over time-therefore it makes the most sense for them to use a bar graph. They are also looking at the frequency of mushers from each location. Here is a bar graph that best shows their data.

Next, we can look at the girls. The girls are looking at how the number of teams that has entered the Iditarod has changed over time. They are comparing data that has changed. When we compare data and how it changes, we use a line graph. That is the best way to show this data.

Vocabulary

Bar Graph
a graph designed to compare data and show the frequency of the data.

Guided Practice

Here is one for you to try on your own.

Look at this graph at the number of hours students volunteered in different grades. In which grade did students volunteer the most?

Answer

The students in the sixth grade volunteered the most hours.

Video Review

This is a Khan Academy video on reading bar graphs.

Practice

Directions: Use the bar graph to answer the following questions.

1. How many different types of vegetables are on the graph?

2. What is the range of the data?

3. What vegetable was the most popular?

4. Which one was the least popular?

5. How many carrots were picked?

6. How many potatoes?

7. How many squash?

8. If ten more zucchini was picked, how would this change the data??

9. If each category doubled, what would the new values be?

10. If each category was divided in half, what would the new values be?

11. What was the total number of vegetables picked?

12. What is the difference between carrots and zucchini picked?

13. What scale was used for this graph?

14. What interval was used in the scale?

15. What is the difference between carrots and potatoes?

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