Keystones — Capstone
Five GCSE retrieval questions · 7 January 2026 · mathsvault.uk/keystones
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1. Number Error intervals
54 is rounded to the nearest integer. What is the error interval?
Answer: 53.5 ≤ x < 54.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 33 and 3x - y = 22
Answer: x = 9, y = 5 -
3. Geometry Distance between two points
Find the distance between (-1, 1) and (6, 5)
Answer: 8.06 -
4. Ratio Repeated percentage change
A car worth £9,986.00 depreciates by 19% each year for 3 years. What is it worth after 3 years?
Answer: £5,306.97 -
5. Statistics Expected frequency
A bag has 5 red out of 9 balls. If you pick 128 times (with replacement), how many times would you expect red?
Answer: 71.1