Question 33
MediumOriginal questionAditi, Balwinder, Chinmay, Dolma and Emmanuel live in a five-storey building, one person on each floor. The ground floor is floor 1, and the numbers increase going up. 'Above' or 'below' means anywhere above or below; 'immediately above' or 'immediately below' means the very next floor. The following is known:
1. Dolma lives on the top floor.
2. Aditi lives immediately above Chinmay.
3. Emmanuel lives above Aditi but below Balwinder.
4. Emmanuel lives on an odd-numbered floor.
Which one of the following clues could be taken out of the list, with every person's floor still fixed by the remaining clues?
Show the answer and explanation
Correct answer: A
Explanation
Clues 1, 2 and 3 alone already give Chinmay 1, Aditi 2, Emmanuel 3, Balwinder 4, Dolma 5; the solving above never used clue 4.
Without clue 1, Dolma need not be on top: Chinmay 1, Aditi 2, Emmanuel 3, Dolma 4, Balwinder 5 also fits.
Without clue 2, Aditi 1, Chinmay 2, Emmanuel 3, Balwinder 4, Dolma 5 fits. Without clue 3, Emmanuel 1, Chinmay 2, Aditi 3, Balwinder 4, Dolma 5 fits.
So only the clue about Emmanuel's odd-numbered floor can be removed.
Worth noting
A clue that the solution never used is the candidate; then check that every other clue really is needed.
- Concept
- Spotting a redundant clue
- Typical timeTypical
- 90 s
- Your timeYours
- —
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