What will the sex ratio in this country be? More males or females?

Steven G

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In a certain country, each couple stops having children if and only if they have a female. After many generations, what will the sex ratio in this country be?

Will the answer be:
significantly more males than females
significantly more females than males
approximately 1:1
 
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In a certain country, each couple stops having children if and only if they have a female. After many generations, what will the sex ratio in this country be?

Will the answer be:
significantly more males than females
significantly more females than males approximately 1:1

In family with no child M = F

In family with 1 child M < F

In family with 2 children M = F

In family with 3 children M > F

In family with 4 children M > F .... so on.

Thus - I think ther will be significant more males than females.
 
In any generation there will be 50% males and 50% females. So, 1:1 in the long run.
 
The expected number of males before a female works out to 1; so the ratio will be 1:1.

Also, as lev888 implied, each individual birth has an equal chance of being male or female, and the policy of stopping after a female can't change that! All it does is, in effect, pass the baton on to another family, who will continue with the same probabilities at each birth.
 
In family with no child M = F

In family with 1 child M < F

In family with 2 children M = F

In family with 3 children M > F

In family with 4 children M > F .... so on.

Thus - I think there will be significantly more males than females.

But ... those families with one child will constitute half of all families! And the families with more males than females constitute only a quarter.

Isn't probability fun?
 
The expected number of males before a female works out to 1; so the ratio will be 1:1.

Also, as lev888 implied, each individual birth has an equal chance of being male or female, and the policy of stopping after a female can't change that! All it does is, in effect, pass the baton on to another family, who will continue with the same probabilities at each birth.
I knew you would know this one. Probability is fun!
 
In family with no child M = F

In family with 1 child M < F

In family with 2 children M = F

In family with 3 children M > F

In family with 4 children M > F .... so on.

Thus - I think ther will be significant more males than females.
Start off with 100,000 families.

They will have (on average) 50,000 daughters and 50,000 sons. So far, 50,000 daughters and 50,000 sons.

The 50,000 families with sons will then have 25,000 daughters and 25,000 sons. So far 75,000 daughters and 75,000 sons.

The 25,000 families with sons will then go on to have 12,500 daughters and 12,500 sons. So far 87,500 daughters and 87,500 sons.

....

The answer is 1:1 (for Denis, it is pi : pi )
 
Agree. No sisters but alotta brudders....
You mean 1 sister but alotta brudders. And even that is wrong. I expect more from you as you are my mentor. Maybe sitting in the corner a bit will help.
 
You mean 1 sister but alotta brudders. And even that is wrong. I expect more from you as you are my mentor. Maybe sitting in the corner a bit will help.
It never has before.
 
You mean 1 sister but alotta brudders. And even that is wrong. I expect more from you as you are my mentor. Maybe sitting in the corner a bit will help.
Actually what he ought to mean is either no sisters (first born is a girl), 1 sister and 1 brother (second born is a girl), or 1 sister and multiple brothers (pity the poor parents when they are up to 10 sons).
 
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Actually, what I meant (without doing any thinking!) is that in
any family, there would be no sisters and possibly n brothers
if the female was the (n+1)th born...

Thanks to my mentor (menteur in French?) Jomo
who presumably was born before his sister :p
I see what you did there. "Menteur" indeed.
 
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