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Thread: When is Cheryl's birthday ??

  1. #1
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    When is Cheryl's birthday ??

    It was meant to be a question to test teenagers at an elite high school in Singapore.

    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 15/16/19

    June 17/18

    July 14/16

    August 14/15/17

    Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.

    Here are the hints ;

    - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't 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 ?


    It took me one freaking afternoon to get the answer !!!

    Try not to find the answers from Internet....
    Chinese tea is good, lager beer is better, 香檳 is the best..

  2. #2
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    Nice puzzle.
    The first 2 hints are actually important to solving it.
    I think I solved it (did not Google for the answer) but will not post - give others a chance to work it out

  3. #3
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    Who is Cheryl??

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    Quote Originally Posted by cskok8 View Post
    Who is Cheryl??
    I think she is her mother's daughter..
    Chinese tea is good, lager beer is better, 香檳 is the best..

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    Quote Originally Posted by kwchang View Post
    Nice puzzle.
    The first 2 hints are actually important to solving it...
    Half of the 1st hint is actually redundant.

    The 2nd and 3rd hint help to eliminate the unknowns and irrelevant possibilities.
    Chinese tea is good, lager beer is better, 香檳 is the best..

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    that 3 timing bitch! She told me, I am the only one!
    in luv with bikes...in lust with AphroditeS AWAS! Suspek is an Avid procurer to myths, lies, legends, folklores, i-ching, rumors, misinformation, cakap-ayam, spɹoʍ uʍop ǝpısdn puɐ˙˙DLL .
    p/s Take all the above with a XL salted duck egg, wash down with 2fingers of sodium hypochoride, and suck on to a pebble size tmn negara Rock salt

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    Quote Originally Posted by opulant View Post
    Half of the 1st hint is actually redundant.

    The 2nd and 3rd hint help to eliminate the unknowns and irrelevant possibilities.
    If you see my explanation, you will see that the 1st and 2nd hint is very necessary

  8. #8
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    I think this question was originally a Primary 6 exam question. It went viral because of a DJ posted it in his Facebook. There was a lot of discussion in the social media should this kind of question for primary school kids even the adults are finding it difficult to answer. Though it means to filter the top 40% students (I can’t remember was it top 20 or 40 percentile).

    PSLE (or Primary School Leaving Examination) is set by our local institution unlike Singapore GCE O & A level which are set by Cambridge. The pressure on the kids are mounting to the extend that some parents are taking leaves during PSLE examination period. Even the newspaper or radio are talking about it when come to the PSLE examination period.

    Personally, I think our local examiners are overdoing it which make the kids “mathphobia”
    有才而性缓定属大才,有智而气和斯为大智.

  9. #9
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    My kid showed me this question which was given by his replacement math teacher when the math teacher was on medical leave. I guess the teacher picked this question from the Internet..

    It's shocking to know this is a question for PSLE. It took me more than 1 hour to find the answer and this is done without the time pressure in exam... !!
    Chinese tea is good, lager beer is better, 香檳 is the best..

  10. #10
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    Quote Originally Posted by opulant View Post
    My kid show me this question given by his replacement teacher when the math teacher was on medical leave. I guess the teacher picked this question from the net..

    It's shocking to know this is a question in PSLE. It took me more than 1 hour to find the answer and this is done without the pressure of time in exam...
    This is just one of the questions. If you happen to see some other PSLE math papers, you probably will vomit blood. Once, I took a math exam paper and ask one of the principals whether if he knows how to solve the question (just for fun)....anyway, examination board is an independent body and no one has authority to question except the Perm Sec. It is also the integrity of our Education System.
    有才而性缓定属大才,有智而气和斯为大智.

  11. #11
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    Quote Originally Posted by opulant View Post

    Here are the hints ;

    - Albert: I don't know when Cheryl's birthday is, but I know that Bernard doesn't 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.
    Quote Originally Posted by kwchang View Post
    If you see my explanation, you will see that the 1st and 2nd hint is very necessary
    Without revealing how I solve the question, I think I can briefly share my thought on hint #1

    When Albert said " I don't know when Cheryl's birthday is, but I know that Bernard doesn't know too ", the 1st half of this hint is redundant, i.e. it has no help to the solution.

    This is because since Cheryl only told Albert the month of her birthday, and every month is given more than one choice, of course Albert wouldn't know her birthday.

    This is what I mean in post #5.
    Chinese tea is good, lager beer is better, 香檳 is the best..

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    Quote Originally Posted by HTCHONG View Post
    This is just one of the questions. If you happen to see some other PSLE math papers, you probably will vomit blood. Once, I took a math exam paper and ask one of the principals whether he know how to solve the question (just for fun)....anyway, examination board is an independence body and no one has authority to question except the Perm Sec. It is also the integrity of our Education System.
    I think I mentioned before I teach my kid mathematics based on Singapore syllabus, on top of what he learns from school.

    Singapore syllabus is designed one year ahead than Malaysia and two years ahead than other countries like New Zealand. There is not much difference between the content of math and Additional math that I learned last time with the current Singapore math syllabus except Singapore students learn it earlier, and the standard set for the maths is higher.

    I think for most exam/assessment in science and mathematics, there will be some very tricky questions (normally around 5% of the total questions). Those who are exceptionally good in that subject will stand up. From my experience, this sort of very tricky question do not need to study, it is application of common sense. Of course, the depth of individual's common sense is different, it depends on raw talent and effort spend on that subject.
    Chinese tea is good, lager beer is better, 香檳 is the best..

  13. #13
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    Quote Originally Posted by opulant View Post
    I think I mentioned before I teach my kid math based on Singapore syllabus.

    Singapore syllabus is designed one year ahead than Malaysia and two year ahead than other countries kike New Zealand. Basically, there is not much difference between the math/add. math I learned with the Singapore content except Singapore students learned them earlier.

    In every exam/assessment, there wil be very tricky questions (normally around 5% of the total questions). Those who are exceptionally good in that subject will stand up. However, majority will be in the 80-95% if they are good.
    I think the math for secondary education is pretty ok. It is the math for primary education that makes a lot of people fed up. In Singapore, the math curriculum in primary education is using “spiral” model which for the same topic it drills and drills and get deeper as the student progresses. That makes many kids worry and in fact it makes some loss confidence. That was what I mean by “mathphobia” for some students.
    Having said that I don’t think the master plan will change at least for the next 5 years, Singapore changes the syllabus every 5-yearly though there may be some minor charges in between.
    有才而性缓定属大才,有智而气和斯为大智.

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    Quote Originally Posted by HTCHONG View Post
    I think the math for secondary education is pretty ok. It is the math for primary education that makes a lot of people fed up. In Singapore, the math curriculum in primary education is using “spiral” model which for the same topic it drills and drills and get deeper as the student progresses. That makes many kids worry and in fact it makes some loss confidence. That was what I mean by “mathphobia” for some students.
    Having said that I don’t think the master plan will change at least for the next 5 years, Singapore changes the syllabus ever 5 yearly though there may be some minor charges in between.

    Not everyone is good in maths, just like not everyone can sing well or draw well.

    Yes, it is tough for the young children.

    I guess the beneficiaries are the tution centres and tuition teachers...
    Chinese tea is good, lager beer is better, 香檳 is the best..

  15. #15
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    Quote Originally Posted by opulant View Post
    Not everyone is good in maths, just like not everyone can sing well or draw well.

    Yes, it is tough for the young children.

    I guess the beneficiaries are the tution centres and tuition teachers...
    Yes, $1 Billion dollar industry. Believe it or not?

    Anyway, I feel sorry for the young children especially those from the needy families who can’t afford tuition. I ask my kids (no longer kid but young adolescent) to provide free tuition at some charity organization for the young children from needy families. I guess this much I can do for them.
    有才而性缓定属大才,有智而气和斯为大智.

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