Keystones — Capstone
Five GCSE retrieval questions · 31 October 2026 · mathsvault.uk/keystones
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1. Number Error intervals
38 is rounded to the nearest integer. What is the error interval?
Answer: 37.5 ≤ x < 38.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 42 and 3x - y = 19
Answer: x = 9, y = 8 -
3. Geometry Distance between two points
Find the distance between (1, -5) and (8, 11)
Answer: 17.46 -
4. Ratio Repeated percentage change
A car worth £17,312.00 depreciates by 10% each year for 5 years. What is it worth after 5 years?
Answer: £10,222.56 -
5. Statistics Expected frequency
A bag has 2 red out of 13 balls. If you pick 103 times (with replacement), how many times would you expect red?
Answer: 15.8