<meta http-equiv="refresh" content="1; url=/nojavascript/">
You are reading an older version of this FlexBook® textbook: CK-12 Middle School Math Concepts - Grade 8 Go to the latest version.

# 1.1: Interpret Given Bar Graphs

Difficulty Level: Basic Created by: CK-12
%
Progress
Practice Bar Graphs
Progress
%

Have you ever had a part-time job? Sometimes students are only allowed to work a certain number of hours based on age. Did you know this?

Take a look at this bar graph.

Do you know how to interpret the data? What conclusions can you draw by looking at the data? Bar Graphs can be very useful once you know how to use them, and here you'll learn all about them.

### Guidance

In the real world, we work with data all the time. What are we talking about when we use that word, “data”? We are referring to statistics or information that has been gathered about real events.

Data is any information that is collected.

When we conduct a survey or measure distances over time or record how trends change, this recorded information is considered data. The big idea is that data is collected information and in this Concept you are going to learn how to organize, analyze and work with data.

Let’s start by thinking about bar graphs. You have probably been working with bar graphs since elementary school, but do you remember the purpose of a bar graph? How does a bar graph display and record information?

Let’s begin with the definition of a bar graph.

What is a bar graph?

A bar graph is a graph that uses columns to show comparison of quantities or amounts.

The key word here is comparison. If you can remember to think about comparing when working with a bar graph, it will help you to keep things straight.

Take a few minutes to write the definition of a bar graph down in your notebook. Be sure to underline the word “comparison” to help you in remembering a bar graph’s purpose.

Take a look at this situation concerning air travel.

The bar graph below compares the air travel costs to fly to numerous U.S. cities from Oakland, California on three airlines. Use the information on the bar graph to answer the questions below.

#### Example A

For which city did all three airlines have a similar price?

Solution: All three airlines had a similar price for travel to Atlanta.

#### Example B

Which airline had the lowest price for three of the five cities?

Solution: Coast to Coast Airlines had the lowest price ticket to Las Vegas, Houston, and Orlando.

#### Example C

For which city did Western Airlines and Coast to Coast Airlines have a difference in price of forty dollars?

Solution: The price of ticket to Orlando on Western Airlines was forty dollars more than a ticket on Coast to Coast Airlines.

Now let's go back to the dilemma from the beginning of the Concept. Here is the bar graph on part-time jobs.

Take a good look at this graph. Now we are going to use the graph to answer the following questions.

How many more hours per week are seniors aloud to spend working than sophomores?

Seniors are allowed to spend twenty hours per week working. Sophomores are allowed to work twelve hours per week. Therefore, seniors are allowed to work eight more hours each week than sophomores.

Are juniors allowed to work twice as many hours as freshman?

Juniors are permitted to work fifteen hours per week. Freshmen are permitted to work eight hours per week. The amount of time freshmen are allowed to work doubled is sixteen. Therefore, juniors are permitted to work almost double the amount freshman are allowed to work, but not quite.

You can see how the visual display of the information is helpful in answering questions about the data.

### Vocabulary

Data
information that has been collected regarding an occurrence or an event.
Bar Graph
is a graph that uses columns to compare quantities or amounts.

### Guided Practice

Here is one for you to try on your own.

The Iditarod is a dog sled race that takes place each year in Alaska. Each year, the organizers of the race survey the mushers entered in the competition to identify each leader's home. Take a look at this bar graph displaying the data collected. Then use it to answer the following questions. Because you don't have a list of the exact data, approximate each value on the bar graph to the best of your ability.

How many mushers come from Alaska?

In this race, how many come from states or countries other than Alaska?

What was the total number of mushers entered in this race?

Solution

There are approximately 27 mushers from places other than Alaska. Fourteen from other US States and about thirteen from other countries.

In total, there were approximately 86 mushers in this race.

### Practice

Directions: Look at each bar graph and use it to answer the following questions.

1. What was the average price of gasoline in Hawaii?

2. What was the average price in Florida?

3. Which state had the lowest average price per gallon?

4. Which state had the highest average cost per gallon?

5. If the average cost in Missouri is $3.00 per gallon, what would 15 gallons cost you in Missouri? 6. Would it be cheaper to buy ten gallons in Hawaii? 7. How much would it cost you to purchase the ten gallons in Hawaii? 8. If the average cost is$3.40 per gallon in California, what would be the difference between ten gallons in Hawaii and ten gallons in California?

9. What is the average price per gallon in Washington state?

10. Based on the bar graph, which state has a cheaper price per gallon, Florida or Washington?

Directions: This graph shows how the number of teams participating in the Iditarod has changed over time. Use this bar graph to answer the following questions.

11. About how many teams participated in 2006?

12. Which year had the highest participation?

13. If the number of teams in 2008 had doubled in 2010, how many teams would have participated in 2010?

14. True or false. There has been a steady increase in participation from 2007 to 2010.

15. If the participation in 2011 increased 10 mushers from the number counted in 2010, how many mushers would be participating?

16. True or false. There were less mushers participating in 2006 compared with 2007.

17. Which statement best describes the participation in 2009?

A. It was better than in 2007.

B. There were less than 80 mushers registered.

C. It was the smallest number of mushers recorded on the graph.

D. Both B and C.

### Vocabulary Language: English

Analyze

Analyze

To analyze is to look at data and draw conclusions based on patterns or numbers.
bar graph

bar graph

A bar graph is a plot made of bars whose heights (vertical bars) or lengths (horizontal bars) represent the frequencies of each category, with space between each bar.
Data

Data

Data is information that has been collected to represent real life situations, usually in number form.

Basic

Dec 19, 2012

Feb 26, 2015