Keystones — Capstone
Five GCSE retrieval questions · 26 October 2026 · mathsvault.uk/keystones
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1. Number Error intervals
68 is rounded to the nearest integer. What is the error interval?
Answer: 67.5 ≤ x < 68.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 31 and 3x - y = 19
Answer: x = 8, y = 5 -
3. Geometry Distance between two points
Find the distance between (-1, -8) and (11, 5)
Answer: 17.69 -
4. Ratio Repeated percentage change
A car worth £19,212.00 depreciates by 12% each year for 3 years. What is it worth after 3 years?
Answer: £13,092.44 -
5. Statistics Expected frequency
A bag has 2 red out of 15 balls. If you pick 149 times (with replacement), how many times would you expect red?
Answer: 19.9