GraphsGraphs

Ok, let’s apply this information to Ok, let’s apply this information to graphs. We’re going to talk about 3 graphs. We’re going to talk about 3 different types of graphs…different types of graphs…

• LineLine graphs graphs

• BarBar graphs graphs

• Pie charts or Pie charts or CircleCircle graphs graphs

GraphsGraphs What are some What are some

subjects that subjects that you might find you might find graphs being graphs being used?used?

What kind of What kind of graphs have you graphs have you seen before?seen before?

Line GraphsLine Graphs

Line graphs are used to show Line graphs are used to show trendstrends..

A A trendtrend is the general is the general directiondirection that that something movessomething moves

Line graphs usually show how Line graphs usually show how something changes over something changes over timetime..

Line GraphsLine Graphs So, you might find line graphs So, you might find line graphs

describing how…describing how…

• Car sales increase or decrease over Car sales increase or decrease over timetime

• How the stock market goes up or How the stock market goes up or downdown

• How much the How much the population population increases each increases each yearyear

Line GraphLine Graph

So… how are So… how are these graphs set these graphs set up?up?

Line graphs have Line graphs have a a horizontal axishorizontal axis and a and a vertical vertical axis.axis.

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Line GraphsLine Graphs

• The The horizontal axishorizontal axis goes across the goes across the bottombottom of the graph… think of the of the graph… think of the horizon…horizon…

• The The vertical axisvertical axis runs runs up and downup and down along the side of the graphalong the side of the graph

Line GraphLine Graph

The The independent independent variablevariable is labeled is labeled on the on the horizontal horizontal axis.axis.

The The dependent dependent variablevariable is labeled is labeled on the on the vertical axis.vertical axis.

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Which axis?Which axis?

So, if we used a line graph to So, if we used a line graph to describe how the describe how the populationpopulation increases each year…increases each year…

What axis would the year be on?What axis would the year be on?

The X- axis!

Labeling the AxisLabeling the Axis

Both Both axisaxis should be should be numbered in numbered in even even intervalsintervals..

This means they This means they should have should have even even spacingspacing of numbers of numbers along the axis.along the axis.

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1980 1985 1990 1995

Ordered pairsOrdered pairs from a data table are from a data table are plotted on the graph and a plotted on the graph and a lineline is drawn to is drawn to connect the data points. connect the data points.

The line shows a trend or relationship The line shows a trend or relationship between the two variables.between the two variables.

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1980 1985 1990 1995

Bar GraphsBar Graphs

Now let’s Now let’s talk about talk about Bar Graphs…Bar Graphs…

Bar GraphsBar Graphs

Bar graphs are used Bar graphs are used to show to show differences differences between eventsbetween events or or individuals.individuals.

Bar graphs are Bar graphs are useful for useful for comparing comparing information collected information collected by counting.by counting.

Bar GraphsBar Graphs

For instance, a bar graph could be For instance, a bar graph could be used to used to comparecompare how many baskets how many baskets were made by 5 different people in a were made by 5 different people in a free-throw competition.free-throw competition.

Or, a bar graph could be used to Or, a bar graph could be used to compare the populations ofcompare the populations of several several different cities.different cities.

Bar GraphsBar Graphs

Each bar in a bar graph represents a Each bar in a bar graph represents a number counted at a particular number counted at a particular time…time…

This would include the This would include the number of number of free-throwsfree-throws each person shoots… each person shoots…

Or, Or, the populationthe population of the cities being of the cities being compared.compared.

Bar GraphsBar Graphs

Similar to the line graph, the Similar to the line graph, the independent variableindependent variable is labeled along is labeled along the the horizontalhorizontal axis. axis.

The The dependentdependent variable is labeled variable is labeled along the along the verticalvertical axis. axis.

Free Throw ExampleFree Throw Example

In our example of In our example of the free-throw the free-throw comparison, which comparison, which variable would be variable would be independent?independent?

Which would be the Which would be the dependent variable?dependent variable?

Free Throws ExampleFree Throws Example

Remember… we are comparing how Remember… we are comparing how many free-throws (or baskets) are many free-throws (or baskets) are made by each person.made by each person.

Which variable Which variable “stands alone”“stands alone” and and which which “relies”“relies” on another variable? on another variable?

Free Throw ExampleFree Throw Example

The number of free throws (or The number of free throws (or baskets) that are made baskets) that are made reliesrelies on on which person threw the ball. which person threw the ball.

So, the number of free throws would So, the number of free throws would be our be our dependentdependent variable. variable.

Free Throw ExampleFree Throw Example

The person The person throwing the ball throwing the ball is the is the independentindependent variable.variable.

Free-Throw ExampleFree-Throw Example

Then, how would the axis be labeled Then, how would the axis be labeled for the free-throw example? for the free-throw example? Remember, the Remember, the independentindependent variable variable is labeled on the is labeled on the horizontalhorizontal axis… axis…

Free-Throw ExampleFree-Throw Example

The independent variable (The independent variable (the the personperson) would be labeled along the ) would be labeled along the horizontal (x)horizontal (x) axis. axis.

The dependent variable (The dependent variable (number of number of free-throws madefree-throws made) would be labeled ) would be labeled along the along the vertical (y)vertical (y) axis. axis.

Pie GraphPie Graph

Pie graphs show Pie graphs show different partsdifferent parts of a of a whole amount.whole amount.

Pie graphs can be used for showing…Pie graphs can be used for showing…• Types of cars sold in the USTypes of cars sold in the US• How memory is used on a hard How memory is used on a hard

drivedrive

What are some other comparisons What are some other comparisons that you could use a pie graph for?that you could use a pie graph for?

Pie GraphsPie Graphs

A pie graph A pie graph starts with a starts with a circlecircle..

This represents This represents the the totaltotal amount amount you are looking you are looking at.at.

Pie GraphPie Graph

The pie is then The pie is then divideddivided into into different sized different sized slices to slices to represent represent different partsdifferent parts of of the total the total amount. amount.

Pizza!!Pizza!!

Think of a pizza!!Think of a pizza!!

Let’s say you Let’s say you ordered a pizza ordered a pizza with different with different sized slices sized slices and and different toppings different toppings on each.on each.

Each slice represents something Each slice represents something different because of the different different because of the different topping… but…topping… but…

Each slice is still a part of the Each slice is still a part of the same same pizza.pizza.

They are just They are just different partsdifferent parts of the of the wholewhole pizza. pizza.

Pizza!!Pizza!!

The The sizesize of each slice determines what of each slice determines what fractionfraction of the whole pizza the slice is. of the whole pizza the slice is.

If a slice was took up half of the whole If a slice was took up half of the whole pizza, it would be pizza, it would be ½½ the whole pizza. the whole pizza.

This can also be considered This can also be considered 50%50% of of the whole pizza.the whole pizza.

Pie graphs are very Pie graphs are very similar…similar…

Each slice of the circle Each slice of the circle represents a represents a partpart of a of a whole amount.whole amount.

CarsCars

For instance, a pie graph For instance, a pie graph might look at the color of 100 might look at the color of 100 cars.cars.

Of those Of those 100100 cars… cars…• 25 might be red25 might be red• 25 might be blue25 might be blue• 50 might be white50 might be white

CarsCars

So… there are So… there are 2525 red cars of the red cars of the total total 100100 cars. cars.

If the circle represents the If the circle represents the wholewhole 100 100 cars, what size would the slice be for cars, what size would the slice be for the red cars?the red cars?

It would be 25/100 which is It would be 25/100 which is ¼¼ or or 25%25% of the whole circle.of the whole circle.

CarsCars

Similarly, Similarly, ¼¼ or or 25%25% of the whole of the whole circle would represent the blue circle would represent the blue cars… and…cars… and…

½ or 50% of the whole pie graph ½ or 50% of the whole pie graph would represent white cars.would represent white cars.

The fraction is equal The fraction is equal to the to the number of white number of white carscars divided by the divided by the total number of cars.total number of cars.

So the fraction would So the fraction would be the be the desired amountdesired amount divided by the divided by the total total amount.amount.

The fraction would be The fraction would be

amounttotal

amountdesired