How do you plot cumulative frequency points on a graph?

To plot cumulative frequency points, plot the cumulative frequency against the upper boundary of each class interval.

To start, you need a frequency table that shows the class intervals and their corresponding frequencies. The first step is to calculate the cumulative frequency for each class interval. This is done by adding the frequency of the current class interval to the cumulative frequency of the previous class interval. For the first class interval, the cumulative frequency is simply its frequency.

Next, identify the upper boundary of each class interval. The upper boundary is the highest value that can be included in that interval. For example, if your class interval is 10-20, the upper boundary is 20.

Now, you can plot the points on a graph. On the x-axis, mark the upper boundaries of the class intervals. On the y-axis, mark the cumulative frequencies. For each class interval, find the point where the upper boundary on the x-axis meets the cumulative frequency on the y-axis and plot it.

Once all the points are plotted, you can join them with a smooth curve or straight lines to form the cumulative frequency graph, also known as an ogive. This graph helps you to easily analyse the distribution of data, such as finding medians, quartiles, and percentiles.