Cheryl Is a Good Logic Puzzle Maker and a Bad Friend

cheryl's birthday logic problem
Via: NY Times
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Via NY Times:

Originally, Mr. Kong said this was a problem inflicted on fifth-graders, leading to hand-wringing that Singapore children were way better at math than everyone else in the world and worries that Singapore children were being mentally abused with convoluted logic at a young age.It turned out the problem actually came from a math olympiad test for math-savvy high school-age students.