AQA GCSE Mathematics Paper 3 (Higher), June 2025: Question 2

1 mark · Easy difficulty · Short Answer

Identify the outlier from a given set of temperatures in six cities.

Practise this question

Question

Question 2 displays six temperature values in degrees Celsius: 0°C, −3°C, 0°C, 1.5°C, 23°C, and 4°C. Below the values, the question asks students to write down the outlier, followed by an answer line ending in °C, worth 1 mark.

Mark scheme

Show the mark scheme Mark scheme table for question 2 showing the correct answer of 23(°C) awarded 1 mark (B1).

How to answer it

Identifying an Outlier in a Data Set

📋 What this question tests

This question assesses basic statistical awareness and data interpretation. You need to understand the mathematical definition of an outlier and be able to inspect a list of numerical values (including negative numbers and decimals) to find a value that does not fit the overall pattern of the data.

Question 2 • 1 Mark

Identifying the Outlier

Data: 0°C, −3°C, 0°C, 1.5°C, 23°C, 4°C

✅ Correct Answer

Answer: 23 (or 23°C )

Mark Scheme: B1 for an independent correct answer of 23. The unit (°C) is already printed on the answer line, so writing just 23 scores full marks.

💡 Key Knowledge

  • An outlier is an extreme value that lies significantly outside the overall pattern of the rest of the data.
  • Most of these temperatures cluster very closely around freezing (between −3°C and 4°C).
  • The value 23°C is far higher than any other number in the set, making it an obvious anomaly.

📐 Step-by-Step Method

  1. Order the data from smallest to largest:
    −3°C, 0°C, 0°C, 1.5°C, 4°C, 23°C
  2. Observe the spread of values:
    Five of the temperatures span a very small range of just 7°C (from −3°C to 4°C).
  3. Spot the extreme jump:
    There is a huge leap of 19°C from 4°C to 23°C. Therefore, 23°C is the clear outlier.

🧠 Exam Technique

  • Look at the answer line: Notice that °C is already provided after the blank. You do not need to write units, but if you write 23°C, it is still accepted.
  • Don't overcomplicate: For a 1-mark Foundation tier question, no complex interquartile range (IQR) formulas are required. Visual inspection is sufficient.

❌ Common Errors

  • Confusing negative numbers with outliers: Some students incorrectly write −3 simply because it is negative. However, −3 is only 3 degrees away from 0, whereas 23 is 19 degrees away from the next closest value!
  • Picking decimals or repeated numbers: Selecting 1.5 (because it is the only decimal) or 0 (because it appears twice). An outlier is defined by its numerical distance from other values, not by its formatting.

Topics

Statistics · 3.6 Statistics

Question and mark scheme from the AQA GCSE Mathematics examination, Paper 3 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.