Keystones — Capstone
Five GCSE retrieval questions · 13 April 2026 · mathsvault.uk/keystones
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1. Number Error intervals
90 is rounded to the nearest integer. What is the error interval?
Answer: 89.5 ≤ x < 90.5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 20 and 3x - y = 19
Answer: x = 7, y = 2 -
3. Geometry Distance between two points
Find the distance between (-2, -7) and (8, 12)
Answer: 21.47 -
4. Ratio Repeated percentage change
A car worth £13,372.00 depreciates by 25% each year for 3 years. What is it worth after 3 years?
Answer: £5,641.31 -
5. Statistics Expected frequency
A bag has 5 red out of 10 balls. If you pick 128 times (with replacement), how many times would you expect red?
Answer: 64