Singaporean high-school students were presented with this logic problem in the Singapore and Asian Schools Math Olympiad test paper last week. The test is aimed at the top 40 per cent of students in one of the most mathematically gifted countries in the world.
Here is the question:
Albert and Bernard just become friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.
- May 15, May 16, May 19,
- June 17, June 18,
- July 14, July 16,
- August 14, August 15, August 17.
Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.
Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.
Bernard: At first I don’t know when Cheryl’s birthday is, but I know now.
Albert: Then I also know when Cheryl’s birthday is.
So when is Cheryl’s birthday?
Can you work out the solution? No cheating. No looking up the answer until you have worked out a solution of your own.
For more information see these articles from the Sydney Morning Herald:
- The maths question for Singapore teenagers that has stumped the world
- The solution to the teenage maths question that has stumped the world
Please don’t post the answer in the comments, just let me know how you went with the puzzle.
This article was originally posted on http://www.winthropdc.com/blog.