An easy question on logic puzzles for P2–P3, with a step-by-step solution, diagrams and the answer. The Hua Xia Cup's P4 qualifying round and finals have true-or-false statements and match-scoring questions. A favourite thinking workout, too.
The question
Yan, Sze-ki and Lok live in the same block on their estate: one on floor 10, one on floor 17 and one on floor 20, each on a different floor.
We know:
Sze-ki doesn't live on floor 10, nor on floor 20.
Lok lives higher up than Yan.
Which floor does Yan live on?
Show the hints (2)
💡Hint 1: Find someone left with only one possible floor: which floors are ruled out for them?
💡Hint 2: Once someone has a floor, nobody else can have it. Start with Sze-ki.
Worked solution
Have a go first, then read the solution step by step.
1.Sze-ki is not on 10 or 20, so Sze-ki lives on floor 17.
2.Yan is not on 17 (Sze-ki lives there), and not on 20 (lower than Lok), so Yan lives on floor 10.
3.Lok is not on 10 (higher than Yan, who is on floor 10), and not on 17 (Sze-ki lives there), so Lok lives on floor 20.
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