A question posed to mathletes in Singapore has quickly gone viral all over the world…but can you solve it?
The question was first posted to Facebook, by Kenneth Kong, a TV host in Singapore. The question, via The NY Times:
Albert and Bernard just met Cheryl. “When’s your birthday?” Albert asked Cheryl.
Cheryl thought a second and said, “I’m not going to tell you, but I’ll give you some clues.” She wrote down a list of 10 dates:
May 15 — May 16 — May 19
June 17 — June 18
July 14 — July 16
August 14 — August 15 — August 17
“My birthday is one of these,” she said.
Then Cheryl whispered in Albert’s ear the month — and only the month — of her birthday. To Bernard, she whispered the day, and only the day.
“Can you figure it out now?” she asked Albert.
Albert: I don’t know when your birthday is, but I know Bernard doesn’t know, either.
Bernard: I didn’t know originally, but now I do.
Albert: Well, now I know, too!
When is Cheryl’s birthday?
The answer: screw Cheryl for making her birthday so damn difficult!!!
Actually, the answer is July 16th. But how? The Guardian does a way better job of walking you through how to solve the perplexing math riddle than I ever could.