Practical Brain teasers for parents (& kids)

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Practical Brain teasers for parents (& kids)

Postby ChiefKiasu » Thu Jan 10, 2013 5:55 pm

Speaking of which, can parents solve this completely hypothetical problem?

3 parents want to get into a school with only 2 remaining vacancies. The names of their children are written down and placed in a ballot box.

One of the parents insisted on being the first to draw. The Principal decided to make it more interesting. The parent will get to draw, but if the ballot he opens is his son's name, then his son will be eliminated and the other 2 parents will get the places in the school.

However, before the parent opens the ballot, the Principal will remove one of the remaining 2 ballots in the box that does NOT contain his son's name. The parent will then get to decide to open either the original ballot he removed, or choose to open the last remaining ballot in the box instead.

What should the parent do?
A) Choose to open his original ballot
B) Choose to open the remaining ballot in the box?
C) It makes no difference whether we choose A or B.

:evil:

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Re: Primary 1 English so hard?

Postby SAHM_TAN » Thu Jan 10, 2013 6:03 pm

Does that mean if he open the ballot with one of the other parent's kid's name, that kid will not be able to register with the school ?

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Re: Primary 1 English so hard?

Postby ChiefKiasu » Thu Jan 10, 2013 6:05 pm

SAHM_TAN wrote:Does that mean if he open the ballot with one of the other parent's kid's name, that kid will not be able to register with the school ?


Yes, that is right. He and the other parent's kids will get the vacancy.

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Re: Primary 1 English so hard?

Postby SAHM_TAN » Thu Jan 10, 2013 6:21 pm

ChiefKiasu wrote:
SAHM_TAN wrote:Does that mean if he open the ballot with one of the other parent's kid's name, that kid will not be able to register with the school ?


Yes, that is right. He and the other parent's kids will get the vacancy.


The parent take the ballot from the box or from the P?

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Re: Primary 1 English so hard?

Postby Sun_2010 » Thu Jan 10, 2013 6:22 pm

ChiefKiasu wrote:Speaking of which, can parents solve this completely hypothetical problem?

3 parents want to get into a school with only 2 remaining vacancies. The names of their children are written down and placed in a ballot box.

One of the parents insisted on being the first to draw. The Principal decided to make it more interesting. The parent will get to draw, but if the ballot he opens is his son's name, then his son will be eliminated and the other 2 parents will get the places in the school.

However, before the parent opens the ballot, the Principal will remove one of the remaining 2 ballots in the box that does NOT contain his son's name. The parent will then get to decide to open either the original ballot he removed, or choose to open the last remaining ballot in the box instead.

What should the parent do?
A) Choose to open his original ballot
B) Choose to open the remaining ballot in the box?

:evil:

Chief you testing our IQ ah?

Option B of course , if we trust probability.

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Re: Primary 1 English so hard?

Postby ChiefKiasu » Thu Jan 10, 2013 6:41 pm

SAHM_TAN wrote:
ChiefKiasu wrote:
SAHM_TAN wrote:Does that mean if he open the ballot with one of the other parent's kid's name, that kid will not be able to register with the school ?


Yes, that is right. He and the other parent's kids will get the vacancy.


The parent take the ballot from the box or from the P?


From the box. The one taken by the P has already won a vacancy.

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Re: Primary 1 English so hard?

Postby ChiefKiasu » Thu Jan 10, 2013 6:43 pm

Sun_2010 wrote:Chief you testing our IQ ah?

Option B of course , if we trust probability.


Lol. I'm actually testing common sense. If you have any, you will not get the answer correct. For completeness, I have included a third option (C).

I'm not telling the answer yet. What's your rationale for choosing Option B?

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Re: Primary 1 English so hard?

Postby SAHM_TAN » Thu Jan 10, 2013 7:03 pm

Very stress testing common sense becos I value common sense over IQ LOL.

Hmmmmm I choose A bah

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Re: Primary 1 English so hard?

Postby ChiefKiasu » Thu Jan 10, 2013 8:32 pm

SAHM_TAN wrote:Very stress testing common sense becos I value common sense over IQ LOL.

Hmmmmm I choose A bah


Keke... why did you choose A?

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Re: Primary 1 English so hard?

Postby wonderm » Thu Jan 10, 2013 8:52 pm

I will choose A because 1/3 the chance it is my child's name, if I chose B, the chance is 1/2.

Correct or not?

Not sure if I hope to get the answer right, that means no common sense leh :nailbite:

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