# A student measures the density of a liquid by recording its volume and mass. He takes five readings of the volume using a measuring cylinder. His results are: 48.0 cm³, 48.2 cm³, 48.1 cm³, 51.3 cm³, 48.1 cm³. Identify the anomalous result. Explain what the student should do with this result and why. Then describe how the student can improve the reliability of his final mean volume.

> AQA A-Level Physics (7408) — 3.1.2 Limitations of Physical Measurements · Explain · 5 marks

## Mark scheme (5 marks)

1. Identifies 51.3 cm³ as the anomalous result
2. States the anomalous result should be excluded / not used when calculating the mean
3. Explains that including it would skew / affect the mean, making it less accurate / not a true representation of the true value
4. States that the student should repeat the measurements (more times / increase the number of repeats)
5. Explains that more repeats allow a more reliable mean to be calculated (by reducing the effect of random error)

## Key terms

- [anomalous result](https://www.gradenine.co.uk/glossary/anomalous-result)
- [mean](https://www.gradenine.co.uk/glossary/mean)
- [reliability](https://www.gradenine.co.uk/glossary/reliability)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-measures-the-density-of-aeba0199) · Published by Druglandscape Ltd.