Can You Solve the Math Problem That Has Gone Viral Around the World?

mathe question

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.

(H/T Gawker)