Keystones — Lintel
Five GCSE retrieval questions · 21 June 2025 · mathsvault.uk/keystones
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1. Number Converting to standard form
0.00042
Answer: 4.2 × 10-4 -
2. Algebra Factorising monic quadratics
Factorise: x² + 3x - 10
Answer: (x + 5)(x - 2) -
3. Geometry SOHCAHTOA — missing length
Hypotenuse = 28cm, angle = 40°. Find adjacent side
Answer: 21.4cm -
4. Ratio Mixed ratio problems
Divide 108 in the ratio 1:3:2
Answer: 18, 54 and 36 -
5. Statistics Mean
The mean of 5 numbers is 35. If 4 of them are 27, 40, 39, 21, what is the missing number?
Answer: 48