Cumulative Frequency Graph Lower Quartile. Cumulative frequency quartiles and percentiles cumulative frequency. Reading from the graph the upper quartile is 47.
To find the upper quartile find frac 3 4 of 40 which is the 30th value. Therefore the iqr is 20 bear in mind that this is a rough sketch if you plot the values on graph paper you will get a more accurate value. Plot the cumulative frequency curve.
The cumulative frequency is plotted on the y axis against the data which is on the x axis for un grouped data.
If we draw a cumulative frequency curve we see that the lower quartile therefore is about 17 and the upper quartile is about 37. Calculate the cumulative frequency. We find the lower quartile by finding of the total frequency ie of 100 25 going up the y axis to 25 along to the graph down to the x axis and estimate the x value there. Reading from the graph the lower quartile is 38.
