Histograms and frequency density

Histograms and frequency density

1. histogram = bar chart where the bars can be different widths

2. y axis = frequency density

   • frequency density = frequency / class width
     • frequency = frequency density x class width = area of bar

3. Example

   • this table and histogram show the lengths of beetles in a garden
     • use the histogram to find the missing entry in the table
       • the frequency = the frequency density x the class width
         • so 18 - 15 = 3 = class width
           • frequency density = 8
             • 8 x 3 = 24
               • the missing value is 24

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