Problem 23 · 2010 Math Kangaroo
Stretch
Logic & Word Problems
casework
Andrew, Stefan, Robert and Marko meet at a concert in Zagreb. They come from different cities — Paris, Dubrovnik, Rome and Berlin (not necessarily in this order).
• Andrew and the friend from Berlin arrive first in Zagreb. Neither of these two has ever been to Paris or Rome.
• Robert is not from Berlin, but he arrives together with the friend from Paris.
• Marko and the friend from Paris enjoyed the concert very much.
Which city does Marko come from?
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Answer: D — Berlin
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Hint 1 of 2
Andrew is not from Paris, Rome, or Berlin, so his city is forced.
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Hint 2 of 2
Place each person's city one clue at a time until only Marko's is left.
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Approach: eliminate cities person by person
- Andrew and the Berlin friend are two people, and Andrew hasn't been to Paris or Rome, so Andrew is from Dubrovnik.
- Robert isn't from Berlin and arrives with the Paris friend, so Robert is from Rome.
- That leaves Paris and Berlin for Stefan and Marko; since Marko isn't the Paris friend, Marko is from Berlin.
Mark:
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