Keystones — Lintel
Five GCSE retrieval questions · 10 March 2026 · mathsvault.uk/keystones
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1. Number Product of primes
Write 90 as a product of its prime factors
Answer: 2 × 3² × 5 -
2. Algebra Linear simultaneous equations
Solve: 2x + 3y = 32 and 3x - y = 15
Answer: x = 7, y = 6 -
3. Geometry Pythagoras — short side
Find b if a = 14cm and c = 25cm
Answer: 20.71cm -
4. Ratio Combining two ratios
a:b is 2:3 and b:c is 4:5. Find a:b:c.
Answer: 8:12:15 -
5. Statistics Expected frequency
A bag has 5 red out of 15 balls. If you pick 95 times (with replacement), how many times would you expect red?
Answer: 31.7