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Mathematics · Grades 8–12

Interquartile range

Use medians of the lower and upper halves for this exercise.

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The key idea

Use medians of the lower and upper halves for this exercise.

IQR = Q₃ − Q₁

Worked examples

Data: 34, 45, 56, 67, 78, 89, 100, 111. Using medians of the lower four and upper four values, find the interquartile range.

Q₁ = 50.5; Q₃ = 94.5; IQR = 44

44

Data: 35, 45, 55, 65, 75, 85, 95, 105. Using medians of the lower four and upper four values, find the interquartile range.

Q₁ = 50; Q₃ = 90; IQR = 40

40

Try it yourself

  1. Data: 49, 52, 55, 58, 61, 64, 67, 70. Using medians of the lower four and upper four values, find the interquartile range.

  2. Data: 44, 51, 58, 65, 72, 79, 86, 93. Using medians of the lower four and upper four values, find the interquartile range.

Check your understanding

Answers and marking notes
  1. 12

    Q₁ = 53.5; Q₃ = 65.5; IQR = 12

  2. 28

    Q₁ = 54.5; Q₃ = 82.5; IQR = 28

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.