Forum menu
funkynick - the first one. neither are relevant to this one though.
Smee, I realise you reckon your reasoning comes from the fact you can discount the boy/girl combination of children, can you rationally justify that? I've not read a coherent response to this assertion yet.
Okay then, can you please explain why neither of those sets of probabilities are relevant?
Smee has already admitted that the "Odds are 2:1"
His only bone of contention was that odds of 2:1 are somehow different from a probability of 66%, which it isn't (as shown above).
Note that he also refuses to provide any working or answer any of the direct challenges to his "theories".
So I can only assume that A) he now agrees with us and/or B) he is just playing it dumb as a some mediocre form of trolling.
You have two children, you know that one or more is a girl. This means that at least one of them can't be a boy. This removes the options of boy/boy and boy/girl.
Why does it do this? Forget age. Lets call them kids 1 and 2. 1 is a girl - we know that - they may be the youngest, they may be the oldest it doesn't matter - what does matter is that they are not both. That is why you can remove one of the boy/girl, girl/boy permutations.
You have two children, you know that one or more is a girl.
Correct.
This means that at least one of them can't be a boy.
Yes.
This removes the options of boy/boy
True.
and boy/girl.
Wrong.
Sorry, stepping back in.
WRONG Smee
1 and 2 refers to the order in which they arrive. WE DO NOT KNOW that 1 is a girl, or that 2 is a girl, merely that at least one of them is.
Boy/Boy option is removed, Boy/Girl option is still valid as the lady said "at least one of them is a girl". It was not stated that the first child, nor indeed the second child is the girl, merely that "one of them is".
Therefore Boy/Girl, Girl/Boy and Girl/Girl are all valid options. In 2 of these there is one girl and one boy, therefore a 2 out of 3 chance of there being one of each, therefore a 66.66% chance of there being a boy and a girl, given that she has already told us that "at least one of them is a girl".
Ah! That explains it, you have a fundamental misunderstanding of the question.
You have two children, you know that one or more is a girl.
Yup
This removes the options of boy/boy and boy/girl.
nope
But boy/girl has the same content as girl/boy.... i.e. one girl and one boy. So therefore they are the same.
But boy/girl has the same content as girl/boy.... i.e. one girl and one boy. So therefore they are the same.
Also wrong.
But, but, so many people have explained this subtletly so many times! And I was so proud of my version. Boo hoo hoo! 😥
What about the little tree diagrams! And the big calculation things!
Even the text descriptions were accurate, succintly worded and clear!
You just don't like us! That's it isn't it!
Dear me.
Mike - are you mental? Read what you have written.
I get the idea that most of you are using I just don't agree that it can be used here.
Mike - are you mental? Read what you have written.
I may be. But, I understand the question and the answer, which you seemingly do not.
I get the idea that most of you are using I just don't agree that it can be used here.
Ah, so the world and the laws of mathematics are wrong?
Ok then Mike. Boy/Girl and Girl/Boy - remove the ages of them and what is the difference?
How about this baby.
There are two towns.
Town A
Town B
Town A has two roads leading to it
Town B had only one
Pick a road purely at random
Probability you'll end in town A?
66%!
Think of town A as mixed kids
Think of town B as all girls
the two roads to mixed kids = G/B B/G
one road to all girls = G/G
Wiredchops - you can try answering that question too.
Until now, I have resisted looking at this thread, is it 5 pages of Smee making a fool of himself?
Ok, I'll try.
The position of the child has an inherent value with regards to order alone.
I.e. There is only one possible way of achieving a girl girl child combo when having two children.
There are two possibilities of achieving a mixed sex combo. Namely, G/B B/G
If you remove the ages of the children the only difference is the order in which you have written them down. WHICH IS NOT TO SAY IT RENDERS THEM THE SAME
THe problem is smee you're looking at the end result. Consider the possible ways of getting there, hence my awesome road/town analogy. THEY ARE NOT THE SAME
Ok then Mike. Boy/Girl and Girl/Boy - remove the ages of them and what is the difference?
There is no difference but there is a 50% of it being a girl/boy boy/girl combination compared to a 25% chance of a girl/girl combination, although I assume this attempted explanation will fail
Smee: if you really are serious (which I doubt) then lets do away with all those confusing formulae and look at the raw empirical data in [url= http://spreadsheets.google.com/ccc?key=p_H5o2Sep3PNxPhB1Cjb-Dg ]my fabulous spreadsheet[/url].
Take each row in turn, ask yourself "Does this row contain at least one girl?"
If it does then scratch a tally mark into the wall of your cell (or ask your therapist for a crayon).
Next ask yourself "Does this row contain one girl and one boy?"
If it does then scratch a mark into a different wall.
Once you have done this for all 100 rows you should find that your first wall has a a total of around 75. And the second wall has a total of around 50.
Now ask one of your carers to tell you what 50 out of 75 is as a percentage...
If there is no difference then they are the same. Why would you give one option double the chance of being the correct outcome?
Okay then... take 3 families
Family A has an older boy and younger girl
Family B has an older girl and younger boy
Family C has two girls
If you pick a family at random, what are the chances that you will pick a family with a boy?
If you believe you can discount either family A or family B from this, as you seem to be doing in your examples above, can you give a reason for which family you would discard, and why that one and not the other.
He must be trolling, this is pretty basic stuff.
Ok then Mike. Boy/Girl and Girl/Boy - remove the ages of them and what is the difference?
They are two separate 'routes' to having two children, where one is a boy and one is a girl. That's twice as many 'routes' as there are for having two children who are both girls.
How about:
Family A has one boy and one girl, or one girl and one boy if you prefer - they only have two kids so they can't have both.
Family B has two girls.
All permutations taken into account.
50:50
How about "djglover is correct" as a solution?
What about if they had a ladyboy?
Smee earlier:
[img] 
[/img]
Nope.
Smee.. if B/G is the same as G/B as you claim, and the chances of it occuring are not doubled, then you have either:-
B/B 25%
B/G or G/B 25%
G/G 25%
Which does not total 100%, or:-
B/B 33.3%
B/G or G/B 33.3%
G/G 33.3%
Which does equal 100%.
This is the logical extension of what you are arguing.
Smee.. so you are saying that an older boy/younger girl is the same as an older girl/younger boy?
Smee.. so you are saying that an older boy/younger girl is the same as an older girl/younger boy?
lol. Are you trying to get him to come out?
Yup, I'm off, smee admitted earlier it was 25:50:25 spread earlier, now he's denying it.
Trolling
Good fun though!
Funkynick
If you knew neither childs gender
b/b 25%
b/g 25%
g/b 25%
g/g 25%
You know the gender of one so you are left with
g/b 50%
g/g 50%
bless him
Can the mods link this post to all of George's subsequent posts as a warning either not to take them seriously (as they are trolls) or invalidate the argument being proposed?
I will not change my mind as a result of what others say. You should all know that by now.
Mat - go and do your presentation.
My guess is that he's either too stupid to realise he's looking stupid, or he'll "reveal" that he was trolling all along.
There's a probability in there somewhere....
Aaaah, so you are admitting you are wrong, but won't change your mind anyway.
Excellent.
Get got the result chaps!
😀
Not admitting anything. As a person capable of independent thought I'm happy with my arguement.
2 Mat's (M@'s) on 2 different forums, what's the probability of it being the same person? :p
Needless to say you've upset Tom's mathsist sensibilities
Pretty good I'd say.
Mathematicians, Engineers, Scientists and Midwives will probably all get different solutions the this puzzle. All will think their solution is correct. Can they all be correct? Yes.