Keystones — Capstone
Five GCSE retrieval questions · 17 April 2026 · mathsvault.uk/keystones
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1. Number Error intervals
79 is rounded to the nearest integer. What is the error interval?
Answer: 78.5 ≤ x < 79.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 31 and 3x - y = 8
Answer: x = 5, y = 7 -
3. Geometry Distance between two points
Find the distance between (-8, -1) and (11, 9)
Answer: 21.47 -
4. Ratio Repeated percentage change
A car worth £8,115.00 depreciates by 17% each year for 5 years. What is it worth after 5 years?
Answer: £3,196.53 -
5. Statistics Expected frequency
A bag has 3 red out of 10 balls. If you pick 81 times (with replacement), how many times would you expect red?
Answer: 24.3