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Flashcards · Maths · Statistics

Cumulative Frequency and Box Plots

16 cards

  1. What is cumulative frequency?

    A running total of frequencies.

  2. Where do you plot cumulative frequency points?

    At the upper boundary of each class.

  3. What is the first point on a cumulative frequency graph?

    The lowest value, with a cumulative frequency of 0.

  4. What is the median on a cumulative frequency graph of \(n\) values?

    The value at cumulative frequency \(\dfrac{n}{2}\).

  5. Where is the lower quartile?

    At cumulative frequency \(\dfrac{n}{4}\).

  6. Where is the upper quartile?

    At cumulative frequency \(\dfrac{3n}{4}\).

  7. What is the interquartile range?

    The upper quartile minus the lower quartile.

  8. Why is the interquartile range useful?

    It is not affected by extreme values.

  9. How do you find how many values are above 80 on a cumulative frequency graph?

    Read the cumulative frequency at 80 and subtract it from the total.

  10. What five numbers does a box plot show?

    Minimum, lower quartile, median, upper quartile and maximum.

  11. What does the box in a box plot cover?

    The middle half of the data, from the lower to the upper quartile.

  12. What does a smaller interquartile range mean?

    The data is more consistent.

  13. How should you compare two distributions?

    Compare a median and a measure of spread, with numbers and in context.

  14. What is the 90th percentile of 100 values?

    The value at cumulative frequency 90.

  15. Why draw construction lines on a graph?

    They show the method and earn the marks.

  16. What should the last point on a cumulative frequency graph equal?

    The total number of values.