# A student measures the boiling point of a saltwater solution. She takes six readings using a thermometer. Her results are: 102.3 °C, 102.4 °C, 102.3 °C, 107.1 °C, 102.4 °C, 102.3 °C. Describe how the student should process these results to obtain a reliable value for the boiling point, and explain the decisions she must make along the way.

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

## Mark scheme (5 marks)

1. Identify 107.1 °C as an anomalous result / outlier
2. State that the anomalous result should be excluded / not included in the calculation of the mean
3. State that the mean (average) of the remaining results should be calculated
4. Explain that repeated measurements reduce the effect of random error / improve reliability
5. Recognise the remaining results show good repeatability / the spread of the remaining results is small, suggesting the mean is a reliable value

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