Keystones — Capstone
Five GCSE retrieval questions · 10 January 2026 · mathsvault.uk/keystones
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1. Number Error intervals
70 is rounded to the nearest integer. What is the error interval?
Answer: 69.5 ≤ x < 70.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 14 and 3x - y = 10
Answer: x = 4, y = 2 -
3. Geometry Distance between two points
Find the distance between (1, -3) and (4, 6)
Answer: 9.49 -
4. Ratio Repeated percentage change
A car worth £14,805.00 depreciates by 23% each year for 4 years. What is it worth after 4 years?
Answer: £5,204.41 -
5. Statistics Expected frequency
A bag has 5 red out of 9 balls. If you pick 78 times (with replacement), how many times would you expect red?
Answer: 43.3