Bar graphs

Bar graphs, also called bar charts, compare values by using bars.Bar charts are a little easier to use than pictographs because the latter takes a long time to construct.

Next we show some examples. What you see below is a bar chart

Vertical bar graph
The information displayed in the graph above straightforward. It tells how many days of snow there were for the month of December, January, February, and March

For example,in December there were two days of snow and in February, there were fourteen days of snow.

If the bar does not extend to the next line on the scale, just approximate the value.

For the month of March, the bar does not extend all the way to four. However, a close look shows that the bar is between 4 and 2.

Therefore, a good approximation is 3, or 3 days of snow in March

The bars do not have to be vertical. They can also be vertical as the following:

Horizontal bar graph
Example: Use the bar graphs below to answer the following questions:

Bar graph
What is the scale of the graph?

The scale is on the left of the graph and it is 1 unit.

What is the title of the graph?

The title is "score on a basic math test"

How many student scored 80?

6 students score 80

How many students got 60 on the test?

4 students got 60

How many students took the test?

1 student got 40, 2 students got 50, 4 students got 60, 3 students got 70, 6 students got 80,and 2 students got 90

1 + 2 + 4 + 3 + 6 + 2 = 18

So, 18 students took the test.

Why is there no bar above 100?

If the passing grade is 70, how many students passed?

11 students passed the test. There is no bar above 100 because no one got 100 on the test.

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