Topics / Maths
Averages
Mean, median, mode and range summarise a set of data. Stage 2 questions often work backwards, for example finding a missing number from a given mean.
What is tested
- Mean, median, mode and range
- Finding a missing value from a mean
- Comparing two sets of data
Worked example
Find the mean of 4, 7, 9, 12 and 3.
- Add: 4 + 7 + 9 + 12 + 3 = 35.
- Divide by how many numbers: 35 ÷ 5 = 7.
Answer: 7
Exam-day checklist
- Put the data in order for the median.
- Mean = total ÷ number of items.
- For a missing value, use total = mean × number of items.
- Range = largest − smallest.
Common mistakes
- Finding the median without ordering.
- Dividing by the wrong count.
- Mixing up mean and mode.
Try it yourself
1. Find the median of 3, 9, 5, 1, 7.
Show answer
5
In order: 1, 3, 5, 7, 9. The middle value is 5.
2. The mean of five numbers is 8. Four of them are 6, 7, 9 and 10. What is the fifth?
Show answer
8
Total = 5 × 8 = 40. The four add to 32, so the fifth is 8.
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