Histograms are similar to bar charts apart from the
consideration of areas.
In a bar chart, all of the bars are the same width and
the only thing that matters is the height of the bar.
In a histogram, the area is the important thing.
It is best that Histograms are plotted against frequency
density or relative frequency density.
They should also only be drawn with continuous data.
Discrete or qualitative data can be plotted in Bar Charts
but their bars should not really touch as they aren't
If the class widths are uneven you will need to plot them
against frequency density rather than just frequency.
Frequency Density = Class Frequency
Class Width x Frequency Density = Class Frequency
Exercise 2B Q3, 4, 7, 9, 10, 11, 12