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posted by cmn32480 on Thursday April 16 2015, @01:24AM   Printer-friendly
from the it-seemed-like-the-logical-thing-to-do-at-the-time dept.

A couple of months ago, it was a color-changing dress that blew out the neural circuits of the Internet. Now Kenneth Chang reports in the NYT that a problem from a math olympiad test for math-savvy high school-age students in Singapore is making the rounds on the internet that has perplexed puzzle problem solvers as they grapple with the simple question: "So when is Cheryl's birthday?"

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?

Logical puzzles like this are common in Singapore. The Singapore math curriculum, which has a strong focus on logic-based problem solving, has been so successful that it's been adopted around the world. According to Terrance F. Ross, US students have made strides in math proficiency in recent years, but they still lag behind many of their peers internationally, falling at the middle of the pack in global rankings. In the same PISA report the U.S. placed 35th out of 64 countries in math. "And even though the "Cheryl's Birthday" question may be atypical of the average Singaporean classroom, perhaps it's still worth asking: Are you smarter than a (Singaporean) 10th-grader?"

 
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  • (Score: 0) by Anonymous Coward on Thursday April 16 2015, @10:56AM

    by Anonymous Coward on Thursday April 16 2015, @10:56AM (#171512)

    The very first post here approaches the solution in a far more practical manner. We do not deal in riddles.

    I'm guessing you're not from Singapore, then.

    People want clear and specific information; they don't like to guess. It is not even practical to guess, as reliability of the solution becomes dependent on the fuzzy input.

    If you think this story has *anything* to do with guesswork, then you're *really* not the intended audience for logic puzzles.

  • (Score: 0) by Anonymous Coward on Thursday April 16 2015, @02:19PM

    by Anonymous Coward on Thursday April 16 2015, @02:19PM (#171596)

    It's guesswork because you have to make all sorts of assumptions to hopefully answer in the way they wanted you to answer. See a bunch of other replies on the assumptions you have to make.

    • (Score: 3, Funny) by tftp on Thursday April 16 2015, @05:21PM

      by tftp (806) on Thursday April 16 2015, @05:21PM (#171661) Homepage

      It's actually worse than that. Your answer hinges on ALL OF THE RESPONDENTS correctly analyzing the problem and providing you with correct replies. This magnifies instability of the solution.

      Imagine the following exchange at work:

      Boss: Listen, John. We have a customer who is willing to pay us $50M for a job. I need you to figure out how much that job will cost us, so we can bid or no bid on it.
      John: OK, boss, I'm on it.

      John: Hey, Jane, how much this will cost us?
      Jane: John, it will be between ten and a hundred million, but it's an even number. Ask Jill for more.
      Jill: John, it will be not a prime number. Ask Will for more.
      Will: John, if you square this number and then calculate a factorial, it will end in two. Ask James for more.
      . . . . . .

      Boss: So, John, what is it? I'd hate to lose our shirt on this contract if we make a mistake.
      John: Boss, I talked to five hundred and thirty seven people in our company. None of them gave me a specific answer. All I have is a bunch of vague hints. I summarized them in this here spreadsheet. According to my calculations, if I am correct, the answer would be 37 million, and we will make a reasonable profit on it. However three hundred and eighty two answers are the keystone of this solution - if they are wrong then our costs could be anywhere from one million to three hundred million. I hope, boss, that this answers your question.
      Boss: @%$#!!!