Purpose of cumulative frequency

Answer 1

Cumulative Frequency - The purpose is to help understand the total frequency of everything UP TO a given value.

By example:

You could have a list of women heights and the frequency (or probability or fraction of the population) that you'll find women of each height.

Or you could have a list of women heights and the frequency that you'll find women of that height OR SHORTER.

This is "cumulative" in that it adds all the frequencies from zero up to that point. Often cumulative frequency is shown in a graphic rather than as a list of values as above. You might have the axis on the left (Y-axis) go from 0% to 100% and the horizontal axis on the bottom (X-axis) go from 0 cm to 300 cm. The line on the chart would show the percentage of women with heights at or under that X-value, and of course, it would be very close to 0% up to 100cm (assuming adult women), then increase to nearly 100% at 200cm, and be flat at 100% up to 300cm.