WKLF Revision Course 2004

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WKLF Revision Course2004

• Handling Data

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Cumulative Frequency
Cumulative Frequency is a running total of the
frequencies.
The number of people who used the bus five times
or less is 40.
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A Cumulative Frequency Diagram shows how the
cumulative frequency changes as the data values
increase.The data is shown on a continuous
scale on the horizontal axis and the cumulative
frequency is shown on the vertical axis.
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The cumulative frequency curve below represents
the times taken to run 1500 m byeach of the 240
members of the athletics club, Weston Harriers.




Time
(minutes)
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A box and whisker diagram, sometimes called a box
plot.

• First, draw a line with a scale that includes
  both the smallest and largest values of the data.

• Draw vertical lines at the positions of the lower
  quartile, the median and the upper
  quartile.

• Join the tops and bottoms of these lines to form
  the box.

Draw horizontal lines from the middle of the
sides of the box to the smallest and largest
values of the data. These are the whiskers.

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A box and whisker diagram (or box plot) can be
drawn from the median, lower quartile and upper
quartile on a cumulative frequency diagram.
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Now try one of your own.
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The table shows the amount of money, in pounds
(), that families pay for mortgages or rent
each month.

• Draw a cumulative frequency curve for this data
• Estimate the median payment
• Estimate the lower and upper quartiles
• Draw a box plot.