The horizontal axis of a cumulative frequency graph is marked with the class intervals from the data set to be plotted on a continuous scale. Data points are plotted on the upper class boundary. The vertical axis of a cumulative frequency graph is always labelled cumulative frequency. In many ...
on the cumulative frequency curve, find 13 on the y-axis (which should be labelled cumulative frequency). The corresponding 'x' value is an estimation of the median.