Keystones — Capstone
Five GCSE retrieval questions · 14 April 2026 · mathsvault.uk/keystones
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1. Number Error intervals
21 is rounded to the nearest integer. What is the error interval?
Answer: 20.5 ≤ x < 21.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 40 and 3x - y = 16
Answer: x = 8, y = 8 -
3. Geometry Distance between two points
Find the distance between (-7, -4) and (11, 9)
Answer: 22.2 -
4. Ratio Repeated percentage change
A car worth £12,458.00 depreciates by 12% each year for 3 years. What is it worth after 3 years?
Answer: £8,489.78 -
5. Statistics Expected frequency
A bag has 5 red out of 12 balls. If you pick 115 times (with replacement), how many times would you expect red?
Answer: 47.9