frequency density

In a histogram, the area of each bar represents frequency. This means that the frequency of groups of unequal widths are fairly represented.

The first table shows the height of children in a class.

In order to record the information in the form of a histogram, we must first find the width of each group and the frequency density. We use the following formula to calculate the frequency density:

    \text {Frequency density} = \dfrac {\text{frequency}}{\text{width of group}}

The second table shows the additional information and the results.

We can now draw the histogram.