Problem 20 · 2020 Math Kangaroo
Stretch
Logic & Word Problems
casework
Five friends decided to spend their vacation together. In a conversation, Adam said, “Yesterday was Wednesday.” Beto said, “Tomorrow will be Friday.” Carlos said, “The day before yesterday was Tuesday.” David said, “The day after tomorrow is Saturday.” Finally, Eli said, “Today is Monday.” One of them was wrong. Who was wrong?
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Answer: E — Eli
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Hint 1 of 2
Translate each statement into 'today is ___' and see if they agree.
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Hint 2 of 2
Four friends point to the same day; the odd one out is wrong.
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Approach: convert each clue to today's weekday
- Adam (yesterday Wed), Beto (tomorrow Fri), Carlos (day-before-yesterday Tue) and David (day-after-tomorrow Sat) all mean today is Thursday.
- Eli says today is Monday, disagreeing with the other four, so Eli was wrong.
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