Keystones — Capstone
Five GCSE retrieval questions · 28 February 2026 · mathsvault.uk/keystones
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1. Number Error intervals
99 is rounded to the nearest integer. What is the error interval?
Answer: 98.5 ≤ x < 99.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 17 and 3x - y = 9
Answer: x = 4, y = 3 -
3. Geometry Distance between two points
Find the distance between (-1, -1) and (12, 12)
Answer: 18.38 -
4. Ratio Repeated percentage change
A car worth £8,195.00 depreciates by 25% each year for 4 years. What is it worth after 4 years?
Answer: £2,592.95 -
5. Statistics Expected frequency
A bag has 5 red out of 14 balls. If you pick 141 times (with replacement), how many times would you expect red?
Answer: 50.4