Frequency Density (Edexcel IGCSE Maths A (Modular))

Frequency Density

What is frequency density?

• Frequency density is given by the formula

  • 

• Frequency density is used with grouped data (i.e. data grouped by class intervals)

  • It is useful when the class intervals are of unequal width

  • It provides a measure of how dense data is within its class interval

    • relative to the width of the interval

  • For example,

    • 10 data values spread over a class interval of width 20 would have a frequency density of 

    • 20 data values spread over a class interval of width 100 would have a frequency density of 

    • As  

How do I calculate frequency density?

• In questions it is usual to be presented with grouped data in a table

• Add two extra columns to the table

  • one to work out and write down the class width of each interval

  • the second to then work out the frequency density for each group (row)