Maths
Stretch – Mean: Reverse & Combined Problems
Stretch (universal 11+): find a missing value from a mean, and find the mean of combined groups.
MathsAge 11+25 minutes
What this topic covers
- Find a missing value given the mean and the other values (total first).
- Find the new mean when a value is added or removed.
- Find the combined mean of two groups from their means and sizes (weighted, not averaged).
Core concept summaries
Key ConceptsThe Missing ValueAdding or Removing a ValueCombined Groups; the Average-of-Averages Trap
Practice formats pupils may meet
NeurofiED uses varied practice to help pupils apply the idea actively, check understanding and build confidence over time.
clozematchingquiz
Example quiz question
Mean 7 over 4 values; three are 5, 8, 9. Missing?
- 28
- 7
- 6
- 22
Show the answer
Answer: C. 6
28 − 22.