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bioball/cheryls_birthday

Created April 20, 2015 16:46
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Cheryl's birthday
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cheryls_birthday
1. Albert knows the date, but not the month. Otherwise, he wouldn't know for sure that Bernard also doesn't know Cheryl's birthday. There are two dates in there that's unique.
2. Since Bernard knows it's not a unique date, he knows it's not June 18th nor May 19th
3. If you take out those two months, there's only one month left that only occurs once. Since Bernard now knows the month for sure, we know it's in June.
Conclusion: Cheryl's birthday is on June 17th
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