[Closed] The boy-girl puzzle

400?

I have 2 coins one in each hand one is a head what's in my left hand?

im not being shouty and abusive?? what kids you've got mike is irrelevant. don't use childs tactics to make me look wrong because it wont make you look any more right! i wasnt meaning YOUR kids i was trying to make a point, clever dick.

it just goes to show you can't argue with an idiot. girl/boy and boy/girl mean the same thing and thats fundamentally where you are going wrong. a mixed pair is a mixed pair. a boy and a girl sat infront of you will still be a boy and a girl no matter what way you look at it.

I have 2 coins one in each hand one is a head what's in my left hand?

Yes you are being shouty and abusive - and yes you are wrong.

Start with 100 families with no kids and tell me what distribution YOU get after they all have two kids.

im not being shouty and abusive??

So calling me a CRETIN and a PENARSE was a constructive argument was it?

I have 2 coins one in each hand one is a head what's in my left hand?

Good example.

[i]Good example. [/i]

It's the simplest form to explain it but Bomberman's head must have exploded trying to prove 50/50.

Drac - 50:50 chance its a head. 50:50 chance you have a head and a tail.

I was out playing in the snow.

Smee's back! We might get to 500 posts 🙂

drac its either a head or a tail

[i]Drac - 50:50 chance its a head. 50:50 chance you have a head and a tail.[/i]

Read the question and you answer tell me what's wrong.

[i]drac its either a head or a tail [/i]

Correct but please show the odds of what is likely.

head/head 50%
head/tail 50%

[i]head/head 50%
head/tail 50%[/i]

How does that show what is in my left hand?

bomberman - you should probably read the other ten pages before you decide.

Thankfully i don't post on here much these days and didn't get involved in this. Not read past the first page but here is my take;

BB - Disc
BG
GB
GG

So, 2/3 of mixed pair.

Ambiguity lies in the question and how you obtain the information about the child, if the mother is selected for her having a girl (ie. met mother and daughter) then the answer (by logic) is 1/2. But that doesn't apply here, because that wasn't the question.

you showed whats in your left hand - it was a head (LMAO!)

Drac - it is a 50% chance that you will have a head in your left hand.

Following on from that there is a 50% chance that you will have a matching pair.

bomberman: Or tell me how YOU think the 100 families have after one child is born, and after two children.

[i]you showed whats in your left hand - it was a head (LMAO!) [/i]

So you can't explain it then.

you showed whats in your left hand - it was a head (LMAO!)

No he didn't. He just said [i]one[/i] was a girl.

[b]MTT: [/b]Ambiguity lies in the question and how you obtain the information about the child, if the mother is selected for her having a girl (ie. met mother and daughter) then the answer (by logic) is 1/2. But that doesn't apply here, because that wasn't the question.

Correct MTT.

[i]Drac - it is a 50% chance that you will have a head in your left hand.

Following on from that there is a 50% chance that you will have a matching pair. [/i]

No there's not all you know is there's one head, so it eliminates the T/T combination.

[strike]T/T[/strike]

H/H
T/H
H/T

Is the combinations you have left.

sorry my bad. it dosen't show what was in your left hand. is there a point to this? you'd better out it now before you forget.

you showed whats in your left hand - it was a head (LMAO!)

Drac's lack of punctuation is forgivable given that he is on nights, but it may be confusing you bomberman. He said [i]"I have 2 coins; one in each hand. One is a head. What's in my left hand?"[/i]

He didn't say which hand was holding the head.

My lack of punctuation in confusing at the best of times.

[i]sorry my bad. it dosen't show what was in your left hand. is there a point to this? you'd better out it now before you forget. [/i]

Read what I put above and treat L/R how many time does head appear in L column?

it's the question.

So what are the odds that she has a girl and a boy?

in your eyes would the answer be different if the question said "so what are the odds that she has a boy and a girl?"

 

in your eyes would the answer be different if the question said "so what are the odds that she has a boy and a girl?"

Nope, the answer would be the same. 66%

In other words, contents of left hand is 50/50 for Head or Tail, Content of right hand is also 50/50 for Head or Tail

Possible combinations are:
[code]LEFT -- RIGHT
Head -- Head
Head -- Tail
Tail -- Head
Tail -- Tail[/code]

If you know he definitely has a Head in one of his hands then you can eliminate Tail -- Tail - leaving three possible combinations, two of which have Heads in his Left hand. 2 out of 3 = 66%

Nice example Drac.

[i]Nice example Drac. [/i]

Thanks it makes it very simple though so some what kills the challenge.

[i]miketually - Member

Yes, but why would you ask her the original question?

So you can find out who the less intelligent people are.[/i]

What kind of smug coont makes a statement like that?

[i]What kind of smug coont makes a statement like that? [/i]

A clever coont.

Drac, I think you've got a coin in your left hand.

BTW I queried the boy/girl girl/boy thing on page one, I understood the reason I was wrong before the end of the page.

girl/boy and boy/girl are the same, regardless of the 100 families theory. the fact that 100 families spawn 50% mixed, 25% bb and 25% gg has nothing to do with it. there are still 3 options to choose from and when you take them into the context of the question the other 99 families have absolutely nothing to do with it.

and by the way i just flipped a coin and it came out 70/30 in favour of tails, even though the odds were 50/50 so that puts your 100 families theory right out the window. when the question says it's a 50/50 chance it means biologically speaking.

yes but we're not talking about holding each child in a particular left or righ hand! you are adding a left/right variable that simply dosent exist in the original question! if you can't understand this then i guess i'm the more intelligent one!

There is a 100% probability that a higher that average number of people involved in this thread have the memory of a gold fish and forget what they've just said.

Either that or there is one hell of an echo in here. 😀

So not 2 coins then?

[i]yes but we're not talking about holding each child in a particular left or righ hand! you are adding a left/right variable that simply dosent exist in the original question! if you can't understand this then i guess i'm the more intelligent one! [/i]

It does exist the combination is still there but some can't see that.

That and you were still convinced it was 50/50 for the coins.

read the question:

what are the odds that she has a girl and a boy?

not what are the chances that she has girl boy and not boy girl??

[i]not what are the chances that she has girl boy and not boy girl?? [/i]

Or indeed "What are the chances she boy girl and not girl boy?"

It does exist the combination is still there but some can't see that.

i must be one of the blind ones then drac, or maybe you're looking for something that simply isnt there. if i had been so smug from the start of this thread i'd be looking for a way out of admitting i was in the wrong too.

Thing was at the start you claimed it was 0.66 or 66%.

girl/boy and boy/girl are the same IN THE CONTEXT OF THIS QUESTION. the coins comparison does not work because it distinguishes between left and right which adds another variable. a variable which is not in any way aparrent in the OP.

Sadly they're not the same combination but never mind.

girl/boy and boy/girl are the same, regardless of the 100 families theory. the fact that 100 families spawn 50% mixed, 25% bb and 25% gg has nothing to do with it. there are still 3 options to choose from and when you take them into the context of the question the other 99 families have absolutely nothing to do with it.

Yes they do - because you don't know which family you are dealing with and the distribution of those families mean that you are twice as likely to be dealing with a family that has mixed children

Just like in the 4999 girls/1 boy question - the other 4999 matter because they are what gives you the odds.

and by the way i just flipped a coin and it came out 70/30 in favour of tails, even though the odds were 50/50 so that puts your 100 families theory right out the window. when the question says it's a 50/50 chance it means biologically speaking.

F..k me. That's just not the way statistics works. It is 50/50 on every flip - that doesn't mean it will come out exactly 50/50 (otherwise every time you tossed a tail you'd know the next one would be a head).
70/30 is pretty normal variance for such a small sample size - flip it a million times and it will come out a bit closer to 50/50.

"Biologically speaking" the odds aren't actually 50/50 and many other factors effect the outcome.

Thing was at the start you claimed it was 0.66 or 66%.

yes because i was sure that the chances of it being a boy were higher as she had said she had a girl and i was thinking that that lowered the chances of it being a girl twice. I soon saw sense though

mixed
GG
BB (eliminated)

when you look at it like that it's really quite simple

It is 50/50 on every flip - that doesn't mean it will come out exactly 50/50

so why are you using the 100 families theory then?

[i]when you look at it like that it's really quite simple [/i]

But wrong.

The PROBABILITY can be calculated exactly - even if small samples suggest it is something else.

If you throw a Head four times in a row, it doesn't change the probability - the next throw is still just as likely to come up heads or tails - anything else is the [url= http://en.wikipedia.org/wiki/Gambler%27s_fallacy ]Gambler's Fallacy[/url].

The 100 families example perfectly follows the exact probabilities because it makes it easier to calculate. I could have given you an example with 18.7 billion families where 9.238 billion have mixed, 4.616 billion have two boy s and so on, but I didn't think it would help. 🙂

Turn it into percentages from the start if you like: 100% of the families have no children. They spawn. Now 50% have a girl and 50% have a boy.
The ones with one girl spawn, (25% 2Girls, 25% Mixed) and the ones with one boy spawn (25% 2boys, 25% Mixed)

In total we now have:
25% of families have 2 Girls
25% of families have 2 Boys
50% of families have Mixed

Pick one random family and the likelihood of it having Mixed (50%) is twice that of it having 2 Girls (25%).

[b]Smee: [/b]There is a 100% probability that a higher that average number of people involved in this thread have the memory of a gold fish and forget what they've just said.

Indeed Smee, indeed:

[b]Smee: [/b]50:50 end of. Any other solution is just stupid.

[b]Smee: [/b]Odds are 2:1 - which is not the same as a probability of 66%

[b]Smee: [/b]2 possible outcomes 50:50 chance.

[b]Smee: [/b]The only idiocy that is going on is people not realising that both solutions are correct.....

GrahamS - are you stalking me?

As someone who uses stats and probability on a daily basis I have read this thread avidly. I came to it once the answer had been agreed several times and so until now have not felt the need to comment.

But I would now like to say Graham S you truly have the patience of a saint!

Or possibly the stubbornness of a donkey 😕

[img] [/img]

also theres the possibility that out of the cross section of 100 families a certain percentage will have twins/ triplets/ octuplets. Riddle me that one GrahamS

I suggest Bomberman you read the original question in full.

yes Drac i understand the answer now thanks. GrahamS is right but that just makes him a smug git for posting a question that he knew the answer to in the first place.

Ah ok.

Ah bomberman has finally seen the light. Excellent!

Perhaps I am smug git, though I think it would have been a bit sh*t if I'd posted a puzzle that I didn't know the answer to.

Still at least I didn't jump up and down calling people cretins and penarses when in fact I was wrong. 😛

(apology accepted by the way)

GrahamS - what is the probability that you are incorrect? 50:50 per chance? 😉

Smee

In this case GrahamS is most definitely 100% correct, there's no 50:50, or indeed 66.66:33.33 about it 😉

*waves at The Sanity Assassin*