JAMB 2000 · UME · Q46

The cumulative frequency curve represents the ages of 100 students in a school. Which age group do 70%70\% of the students belong to?

15.516.517.518.519.520.520406080100Age (years)Cumulative frequency
Worked solution (try it first)
  1. The number of students in an age group is the cumulative frequency at its top end minus the cumulative frequency at its bottom end.
  2. From the curve, the cumulative frequency is 30 at 17.5 years and 100 at 20.5 years, so 100−30=70100 - 30 = 70 students are aged 17.5–20.5.
  3. That is 70%70\% of 100, option D.
  4. The other groups hold 60, 90 and 82 students.

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