Handling Data 1

3 marks · Normal

A magazine states, 'On average, students in our school have 2.8 siblings.'

Explain what this statement means. Why might the mean not be the best average to use for this data?

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Must show: explanation of mean 2.8, no student can have 2.8 siblings, other averages (mode or median) may be more suitable

Common mistakes: claiming 2.8 siblings is possible; not mentioning other averages

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Marking points

B1 · 1 mark · States the mean is the total number of siblings divided by the number of students.

B2 · 1 mark · Notes that nobody can actually have 2.8 siblings.

B3 · 1 mark · Explains why another average (median or mode) might be more suitable for whole-number data.

Worked solution

The mean is found by dividing the total number of siblings by the number of students, giving 2.8 per student. No individual student has 2.8 siblings because siblings are whole people. The mean can give a misleading impression here, so the mode or median might be better if most students have, for example, 2 or 3 siblings.