Keystones — Capstone
Five GCSE retrieval questions · 1 March 2026 · mathsvault.uk/keystones
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1. Number Error intervals
85 is rounded to the nearest integer. What is the error interval?
Answer: 84.5 ≤ x < 85.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 28 and 3x - y = 9
Answer: x = 5, y = 6 -
3. Geometry Distance between two points
Find the distance between (-5, -6) and (8, 8)
Answer: 19.1 -
4. Ratio Repeated percentage change
A car worth £10,421.00 depreciates by 25% each year for 5 years. What is it worth after 5 years?
Answer: £2,472.95 -
5. Statistics Expected frequency
A bag has 5 red out of 15 balls. If you pick 129 times (with replacement), how many times would you expect red?
Answer: 43