BMAD Posted November 10, 2013 Report Share Posted November 10, 2013 Do men have more sisters then women? 1 2 Quote Link to comment Share on other sites More sharing options...
0 harey Posted November 10, 2013 Report Share Posted November 10, 2013 No. Quote Link to comment Share on other sites More sharing options...
0 Prime Posted November 11, 2013 Report Share Posted November 11, 2013 (edited) Hard to say. Of course, each woman can count several times, if she has several brothers. Judging from the sample of population just around me, the answer is NO. However, that may not be accurate, since I am surrounded by people with zero, or one sibling. Most men I've met have no sisters. Of those who do, most have just one sister. And the general assumption here is that there are about the same number of men and women overall. Edited November 11, 2013 by Prime Quote Link to comment Share on other sites More sharing options...
0 DeGe Posted November 11, 2013 Report Share Posted November 11, 2013 Let's take a global average and say that in average, in a family there are N boys and M girls. Then, each of the N boys have M sisters and each of the M girls have M-1 sisters. Therefore, in average men have more sisters than women. Quote Link to comment Share on other sites More sharing options...
0 phaze Posted November 11, 2013 Report Share Posted November 11, 2013 (edited) @DeGe I think you got caught in his cleverly designed trap Lets try a family of three for an example. If there is the same chance of having boys as girls the following family constructions from oldest to youngest are equally likely. Family Construction Girls v Boys GGG 3 girls * 2 sisters v 0 boys * 3 sisters = 6v0 GGB 2 * 1 v 1 * 2 = 2v2 GBG 2 * 1 v 1 * 2 = 2v2 GBB 1 * 0 v 2 * 1 = 0v2 BGG 2 * 1 v 1 * 2 = 2v2 BGB 1 * 0 v 2 * 1 = 0v2 BBG 1 * 0 v 2 * 1 = 0v2 BBB 0 * 0 v 3 * 0 = 0v0 Total Girls = 12 Total Boys = 12 I'll leave it to you to figure out the formula to use for an arbitrary family size. Edited November 11, 2013 by phaze Quote Link to comment Share on other sites More sharing options...
0 harey Posted November 12, 2013 Report Share Posted November 12, 2013 @bmad: I do not think my answer was the best one - after all, the chances were 50-50 phaze answered much better, he explained WHY. Quote Link to comment Share on other sites More sharing options...
0 BMAD Posted November 12, 2013 Author Report Share Posted November 12, 2013 Fair enough Quote Link to comment Share on other sites More sharing options...
0 phaze Posted November 12, 2013 Report Share Posted November 12, 2013 I think it is still up for grabs, as I have not proven anything but simply given an single example. The prize should go to anyone who can come up with an explanation for families of arbitrary sizes rather than of size 3 Hint: Pascal triangle Quote Link to comment Share on other sites More sharing options...
0 Rainman Posted November 13, 2013 Report Share Posted November 13, 2013 For any n, the probability of having n sisters is independent of your own gender. Hence your expected number of sisters is also independent of your own gender. Quote Link to comment Share on other sites More sharing options...
0 harey Posted November 13, 2013 Report Share Posted November 13, 2013 I think it is still up for grabs, as I have not proven anything but simply given an single example. Myself, I would prove it for N=0 and leave the proof for N>0 to the reader If you try for some N, you quickly see the law. Quote Link to comment Share on other sites More sharing options...
0 bonanova Posted November 18, 2013 Report Share Posted November 18, 2013 Do men have more sisters then women? As stated it depends on how many women the average man has. In my case, I have two sisters, and the second part is classified. ----- I suspect the OP really asks: "On average, who have more sisters: men or women?" Then the answer seems to be: Men have more sisters than women (do). A similar, seemingly true statement is: Men have more sisters than (they have) brothers. Proof: In every family, there are m male children and f female children. Assuming mf =/=0, the m male children each have f sisters; the f female children have (f-1) sisters. Similarly, every female child has m brothers. Since f > f-1 and on average m = f, both statements are true. But do the statements hold true for weighted averages across populations? Let's distribute an equal number (25) of sons and daughters among three families, as follows: Family 1: m=f=10. 10 men each have 10 sis and 9 bro; 10 women each have 9 sis. Family 2: m=2f=10. 10 men each have 5 sis and 9 bro; 5 women each have 4 sis. Family 3: 2m=f=10. 5 men each have 10 sis and 4 bro; 10 women each have 9 sis. 25 men have 200 combined sisters and 200 combined brothers; 25 women have 200 combined sisters. On average, the men have 8 sisters and 8 brothers; the women have 8 sisters. Both statements are false. Quote Link to comment Share on other sites More sharing options...
0 Grimbal Posted November 29, 2013 Report Share Posted November 29, 2013 According to chinese rules that held for a long time, you can have only one child. But if it is a girl, you can have a second one. If the rules are respected, out of 4 families, 2 have one boy only, 1 has one boy and one girl, 1 has two girls. The 3 boys have 1/3 sister on average, the 3 girls have 2/3 sisters on average. Since China represents a non-negligible proportion of the world population, it would seem girls have more sisters on average. Quote Link to comment Share on other sites More sharing options...
0 harey Posted November 30, 2013 Report Share Posted November 30, 2013 @Grimbal You can continue: - there are 50.5 boys born per 49.5 girls. - women live longer. Quote Link to comment Share on other sites More sharing options...
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Do men have more sisters then women?
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