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Thread: Quick Logic Problem

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    Question Quick Logic Problem

    Say that Jane and Joan (who are unrelated) each has two children. We know that at least one of Jane's children is a boy and that Joan's oldest child is a boy. What are the odds that each of the women has 2 boys?

    "To argue against any breach of liberty from the ill use that may be made of it, is to argue against liberty itself, since all is capable of being abused." – Lord George Lyttleton (1709-1773)

    Your children's future
    Total debt:

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    25%.
    My goal in life is to be as good a person as my dog thinks I am.

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    Quote Originally Posted by Thorn View Post
    25%.
    No

    "To argue against any breach of liberty from the ill use that may be made of it, is to argue against liberty itself, since all is capable of being abused." – Lord George Lyttleton (1709-1773)

    Your children's future
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    The chances for "each" would be the same since they'd have to be figured separately.

    It is a 50% chance that each would have two boys.
    Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but rather we have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit.
    - -- Aristotle

    Believe nothing on the faith of traditions, even though they have been held in honor for many generations and in diverse places. Do not believe a thing because many people speak of it. Do not believe on the faith of the sages of the past. Do not believe what you yourself have imagined, persuading yourself that a God inspires you. Believe nothing on the sole authority of your masters and priests. After examination, believe what you yourself have tested and found to be reasonable, and conform your conduct thereto.
    - -- The Buddha

    It is the mark of an educated mind to be able to entertain a thought without accepting it.
    - -- Aristotle

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    Quote Originally Posted by Damocles View Post
    The chances for "each" would be the same since they'd have to be figured separately.

    It is a 50% chance that each would have two boys.
    No

    "To argue against any breach of liberty from the ill use that may be made of it, is to argue against liberty itself, since all is capable of being abused." – Lord George Lyttleton (1709-1773)

    Your children's future
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    Regular logic, or Danologic?

    If it's the latter, there was a lady I used to work with at McDonald's who had 2 boys, so the chances are 100%.

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    Quote Originally Posted by KingCondanomation View Post
    No
    Then you asked the question incorrectly. You did not want the odds figured for "each" you wanted them figured together.

    We know each woman has one boy, and they each have two children. There is a 50% chance that the child we don't know is a boy for each woman. Taken together, Thorn would be correct. .5 X .5 = .25 or 25%. The odds are 1 in 4 when taken together, they are 1 in 2 when taken separately.
    Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but rather we have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit.
    - -- Aristotle

    Believe nothing on the faith of traditions, even though they have been held in honor for many generations and in diverse places. Do not believe a thing because many people speak of it. Do not believe on the faith of the sages of the past. Do not believe what you yourself have imagined, persuading yourself that a God inspires you. Believe nothing on the sole authority of your masters and priests. After examination, believe what you yourself have tested and found to be reasonable, and conform your conduct thereto.
    - -- The Buddha

    It is the mark of an educated mind to be able to entertain a thought without accepting it.
    - -- Aristotle

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    Quote Originally Posted by Onceler View Post
    Regular logic, or Danologic?

    If it's the latter, there was a lady I used to work with at McDonald's who had 2 boys, so the chances are 100%.
    No that's the Danocdotal story remember? Try not to get your strawmen mixed up when you're looking for an easy out to a debate or problem.

    "To argue against any breach of liberty from the ill use that may be made of it, is to argue against liberty itself, since all is capable of being abused." – Lord George Lyttleton (1709-1773)

    Your children's future
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    Quote Originally Posted by Onceler View Post
    Regular logic, or Danologic?

    If it's the latter, there was a lady I used to work with at McDonald's who had 2 boys, so the chances are 100%.

    Win.

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    Quote Originally Posted by KingCondanomation View Post
    No
    I assumed that you meant both would have 2 boys each. So the probability would be 50% for each, sampling without replacement, (.5 x .5) = 0.25
    My goal in life is to be as good a person as my dog thinks I am.

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    Quote Originally Posted by Damocles View Post
    Then you asked the question incorrectly. You did not want the odds figured for "each" you wanted them figured together.

    We know each woman has one boy, and they each have two children. There is a 50% chance that the child we don't know is a boy for each woman. Taken together, Thorn would be correct. .5 X .5 = .25 or 25%. The odds are 1 in 4 when taken together, they are 1 in 2 when taken separately.
    I must admit that I am a little lost here as well. If we are calculating odds based on the given info then it seems thorn should be right with 25%.

    If you are calculating the odds of two women each having two boys, then it is a different equation.

    I've looked at the wording of your question and there seems to be no deception, so I can only assume that you are asking the question incorrectly.
    There is much to be said in favour of modern journalism. By giving us the opinions of the uneducated, it keeps us in touch with the ignorance of the community.

    -Oscar Wilde

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    Quote Originally Posted by Damocles View Post
    Then you asked the question incorrectly. You did not want the odds figured for "each" you wanted them figured together.

    We know each woman has one boy, and they each have two children. There is a 50% chance that the child we don't know is a boy for each woman. Taken together, Thorn would be correct. .5 X .5 = .25 or 25%. The odds are 1 in 4 when taken together, they are 1 in 2 when taken separately.
    No, I know what I asked.

    Here's a hint:
    When you said .5 X .5 = .25 or 25% you are not incorrect.

    "To argue against any breach of liberty from the ill use that may be made of it, is to argue against liberty itself, since all is capable of being abused." – Lord George Lyttleton (1709-1773)

    Your children's future
    Total debt:

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    Quote Originally Posted by KingCondanomation View Post
    No, I know what I asked.

    Here's a hint:
    When you said .5 X .5 = .25 or 25% you are not incorrect.
    1/3 !!!!!
    Quote from Cypress:
    "Scientists don't use "averages". Maybe armchair supertools on message boards ascribe some meaning to "averages" between two random data points. And maybe clueless amatuers "draw a straight line" through two random end data points to define a "trend". Experts don't.

    They use mean annual and five year means in trend analysis. Don't tell me I have to explain the difference to you. "

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    6.25%

    If not I give up.
    There is much to be said in favour of modern journalism. By giving us the opinions of the uneducated, it keeps us in touch with the ignorance of the community.

    -Oscar Wilde

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    Oh great another genius post from Battleborne is en route.
    There is much to be said in favour of modern journalism. By giving us the opinions of the uneducated, it keeps us in touch with the ignorance of the community.

    -Oscar Wilde

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