GCSE · Cumulative frequency & box plots

Quartiles & the interquartile rangeExam-style questions

Why the quartiles are a quarter and three quarters of the way *through the data* rather than along the number line, how to find them from an ordered list and from a cumulative frequency curve, and why the interquartile range beats the range as a measure of spread.

Start practising Read the lesson

8 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 2Level 3Level 4Level 5
  1. 1
    Here are the ages, in years, of the 1111 members of a chess club, written in order:

    9,11,12,14,14,15,17,18,20,21,269, \quad 11, \quad 12, \quad 14, \quad 14, \quad 15, \quad 17, \quad 18, \quad 20, \quad 21, \quad 26

    (a) Write down the median age.

    (b) Work out the interquartile range of the ages.
    Level 2 · 4 marksTry it