A school maths question posted on Facebook by a Singaporean TV presenter Kenneth Kong has stumped thousands around the world after it went viral.
The baffling question for 15 year old students at Singapore and Asian Schools Math Olympiads (SASMO) left many wondering if that's what is expected of schoolkids.
SASMO later said in a Facebook post that Singapore parents wouldn’t worry so much about the difficulty of this question since “Being Question 24 out of 25 questions, this is a difficult question meant to sift out the better students. SASMO contests target the top 40% of the student population and the standards of most questions are just high enough to stretch the students.”
So, the problem is:
Albert and Bernard just became 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, or August 17.Cheryl then tells Albert the month of her birthday, but not the day. She tells Bernard the day of her birthday, but not the month.
Then the following short conversation occurs between Bernard and Labert to figure out Cheryl's birthday.
Albert: I don't know when Cheryl's birthday is, but I know Bernard doesn't know either.
Bernard: At first I didn't know when Cheryl's birthday is, but now I know.
Albert: If you know, then I know too!
When is Cheryl's birthday?
To solve this problem which requires logical and analytical reasoning skills, one should work backwards to deduce Cheryl's birthday by eliminating wrong dates according to the conversation between Albert and Bernard about the information given to them.
Well, if you're struggling to solve it, don’t worry, SASMO posted the the official solution.
If you can't make sense of it, the New York Times has a different approach while the Guardian has a another alternative. A video demo by mathematician Alex Bellos is posted by BBC on its YouTube channel.
If you are deeply interested, you might also want to see it depends on your point of view
