A percentile is a value on a scale of 100 that indicates the percent of a distribution that is equal to or below it.

The lower quartile is the value under which 25% of data points are found when they are arranged in increasing order.  Also known as the first quartile (Q1).

The upper quartile is the value under which 75% of data points are found when they are arranged in increasing order.  Also known as the third quartile (Q3).

Interpreting a cumulative frequency graph

Maths

In the prior unit, pupils compared two different sets of data. In this unit, pupils consider cumulative frequency graphs and histograms and compare these with other known graphical representations.

Graphical representations of data: cumulative frequency and histograms

Use this graph to estimate the lower quartile.

Use this graph to estimate the upper quartile.

Any pupil scoring over 20 marks gets a certificate.  How many certificates are given out?

Cumulative frequency is the total of all frequencies up to a defined class.  It is the '{{ }} total' of frequencies.

What is the missing cumulative frequency?

Plot the cumulative frequency with the mid-point of the group

Plot the cumulative frequency on the vertical axis

Which of the following is not correct when drawing a cumulative frequency graph?

What coordinates should be plotted for the second point?

What coordinates should be plotted for the third point?

Starter Quiz