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HomeOff Topics Jokes-Puzzles-Riddles › Who has more brothers?
01-12-2010 09:11 AM  8 years agoPost 1
spork

rrVeteran

Mountain View, CA

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Assuming for the sake of argument that there are as many girls as boys (and an equal probability for either one for each birth), who has more brothers - girls or boys?

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01-12-2010 12:09 PM  8 years agoPost 2
Yug

rrMaster

UK. Herts

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girls because of n-1, i think

Vegetable rights and Peace

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01-12-2010 01:25 PM  8 years agoPost 3
spork

rrVeteran

Mountain View, CA

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Anyone else?

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01-12-2010 03:53 PM  8 years agoPost 4
HeliFreek

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Baltimore, MD USA

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OK, lets see. 10 boys and 10 girls. Any one of the girls have 10 brothers and any one of the boys would have only 9 brothers.

My answer is the girls would have more brothers.

Mark
AMA 871036

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01-16-2010 06:50 AM  8 years agoPost 5
spork

rrVeteran

Mountain View, CA

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Oops, I guess I forgot about this thread. It ends up that overall girls have the same number of brothers that boys do. In a family of boys and girls, the girls will have more brothers. In a family of all girls, no one has any brothers. And of course in a family of all boys, boys have more brothers. Oddly enough it all works out to be the same for both boys and girls.

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01-19-2010 07:58 PM  8 years agoPost 6
Leif

rrElite Veteran

USA

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The conclusion might be correct, but you didn't really explain the reason for this:

If there are an equal number of boys and girls total, then you would think that girls would have more brothers (for example, all two-child households with one girl and one boy would only count brothers for the girl). This would seem to give an advantage to girls.

This advantage is overriden by the "multiple count" effect. In a family of four boys, each boy has "three brothers" for a total count of 12 brothers....

Leif

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01-19-2010 08:09 PM  8 years agoPost 7
spork

rrVeteran

Mountain View, CA

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The conclusion might be correct, but you didn't really explain the reason for this:
I explained exactly what you just repeated. But neither of us have given an intuitive explanation as to why those two situations balance each other perfectly. I ran a simulation to confirm it - and it works. But I haven't tried to do a closed-form solution to see "why" it works.

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