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5. Graphs

Frequency Table and Histogram

A frequency table is one way to organize large quantities of data

Steps to take: 

1.              Arrange the data into equal intervals

2.              Record the frequency for each interval using tally marks

3.              Count the tally marks and record the frequency

Terms to know:

Statistics:            The study of collecting, analyzing, and presenting data

Data:                   Information, often numerical, which is gathered for statistical purposes

Scale:                 The ratio that compares the measurements on the drawing or model to the
measurements of the real object.

Interval:               The difference between successive values on a scale.  Always the same distance apart.

Tally mark:          A counter used to record items in a group.

You can make a graph to display the information in a frequency table.  This graph is called a histogram.

A histogram is a graph that uses bars to display a set of data that has been organized into frequencies within equal intervals.

Steps to take to make a histogram:

1.              Title your graph

2.              Choose a scale for the vertical axis with equal intervals and label it

3.              Draw and label the horizontal axis with data intervals

4.              Draw a bar for each data interval.

1.  How many circus performers are less than 10 years old?   

2.  Which age group has the most circus performers?  

3.  Which age groups have the same number of performers?  

4.  How many performers are there in the age groups 20-29 and 30-39?  

Your turn, take a survey of 30 people to determine their favorite sport, food, shopping spree, and drink.  Once you have completed the survey, complete the frequency chart.  We will be using this information to create graphs later.  

Comment:  What are intervals? 

Moving on to the Types of Graphs