Countdown to Exams - Day 21 - Cumulative frequency tables and graphs
On day 21 we move on and have a look at Cumulative frequency tables and graphs. This is essentially a running total where we add up the frequencies as we go along. It is important to check to see if your final value of the cumulative frequency matches the total frequency (normally given in the question).
When constructing a cumulative frequency graph, it is important to plot each point at the end of each group and join the points up with a nice smooth curve ('s' shaped). The graph is used to estimate numbers above and below certain values.
Matt explains how to complete cumulative frequency tables and how to plot and use the graphs to extract information about the data.
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