Calculating The Five-Number Summary & Interquartile Range (IQR)

Quiz Scores

Opening

Quiz Scores

These are the quiz score data used in Lesson 4:

{0, 1, 1, 2, 2, 3, 3, 3, 4, 5, 6, 6}

Discuss how the five-number summary is represented in a box plot.

  • The five-number summary for this data:
    • Lower extreme: 0
    • Lower quartile: 1.5 (because the middle pair of values for the lower half of the data is 1 and 2, and 1.5 is halfway between 1 and 2—{0,1,1,2,2,3})
    • Median: 3 (because the two middle numbers are both 3)
    • Upper quartile: 4.5 (because the middle pair of values for the upper half of the data is 4 and 5, and 4.5 is halfway between 4 and 5—{3,3,4,5,6,6})
    • Upper extreme: 6
  • Study the box plot below. Explain to a partner how the five-number summary was used to draw the box plot.
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