Keystones — Capstone
Five GCSE retrieval questions · 30 October 2026 · mathsvault.uk/keystones
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1. Number Error intervals
28 is rounded to the nearest integer. What is the error interval?
Answer: 27.5 ≤ x < 28.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 20 and 3x - y = 19
Answer: x = 7, y = 2 -
3. Geometry Distance between two points
Find the distance between (0, 2) and (8, 10)
Answer: 11.31 -
4. Ratio Repeated percentage change
A car worth £19,368.00 depreciates by 14% each year for 3 years. What is it worth after 3 years?
Answer: £12,319.13 -
5. Statistics Expected frequency
A bag has 4 red out of 9 balls. If you pick 123 times (with replacement), how many times would you expect red?
Answer: 54.7