How do you plot cumulative frequency on a graph?

To plot cumulative frequency on a graph, plot cumulative frequencies against the upper class boundaries of the data intervals.

To start, you need to create a cumulative frequency table from your data. This involves adding up the frequencies of each class interval progressively. For example, if your data intervals are 0-10, 10-20, and 20-30 with frequencies 5, 7, and 3 respectively, the cumulative frequencies would be 5, 12 (5+7), and 15 (5+7+3).

Next, identify the upper class boundary for each interval. The upper class boundary is the highest value that can be included in that interval. For the intervals 0-10, 10-20, and 20-30, the upper class boundaries are 10, 20, and 30 respectively.

Now, on graph paper, draw your axes. The horizontal axis (x-axis) will represent the upper class boundaries, and the vertical axis (y-axis) will represent the cumulative frequencies. Label your axes clearly and choose an appropriate scale for each axis.

Plot each cumulative frequency against its corresponding upper class boundary. For our example, you would plot the points (10, 5), (20, 12), and (30, 15).

Finally, join the points with a smooth curve or straight lines. This curve is known as the cumulative frequency curve or ogive. It helps you to analyse the distribution of data and find medians, quartiles, and percentiles easily.