In one nation, having a daughter is traditionally prefferable to having a son. Therefore, a couple will continue to have children until a daughter is born. Once they have a daughter, they will stop. (Assume that it is possible for a couple to have an unlimited number of children)

If the chance of a boy or a girl being born is equal, what would be the ratio boys to girls in this country?

First off, you're missing immegration and emmigration.  Countries that have rules like this are likely to also have their women very oppressed and niether able to leave, nor wish to stay.  Men will either stay or leave for buissness.  Wars will kill the men.  In general, men just live less long than women.  ... but men and women aren't boys and girls.

Second, there is a semantic problem with a "boy" being born.  But I think anyone who cares understands what I'm saying already.

Third (and my point) is that saying that the chance is "equal" is like saying the word "average".  Average makes people not know if it's the mean, mode, median.  Similarly, by 'equal chance' do you mean to say that all people have a fifty-fifty chance to have a boy (who have a child)?  Or do you mean that the odds are 50-50?  As a biology major, I assure you that niether are true.  51% of the population born are women.  Some men cannot produce gametes with certian sex chromosomes.  Some women produce only one hormone which attracts certian sperm (can be gender selective, studies have even showen that women increase their chances of having a boy or girl by thinking about it).  Therefore, even if we were to assume 50:50 chance of birth, the reality would not be such.  So, equal chances should include a variance (even if we do assume 50% male).
However, even if *this* were true, we would be overlooking the most terrible of animal natures: the desire to make more babies of our own.  Therefore, I contend, that female infants would be killed (murdered?) upon or before birth, thus resulting in a skeded male:female population.
Perhaps a better question would be if 100 people flip a standerd coin, and stopped as soon as it was heads, what would the final ratio of head to tails be?

--Mike

Sorry if my spelling is bad, I forgot that my computer won't let me copy and paste into Word to check it. 

Posted by Mike on 2005-05-09 23:29:54