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Post by asdfg on Jul 14, 2009 12:14:09 GMT
Let’s say you work in a Post Office and a woman comes in to claim her child benefit for her 2 children.
You notice that she has one child with her – a boy.
With this information, would you conclude that her other child is more likely to be another boy, a girl, or can’t you tell?
What level of confidence do you have in your answer (i.e. what’s the probability that you’re right)?
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Post by kensington on Jul 14, 2009 15:05:35 GMT
I would conclude neither and make no assumption on that basis  |
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Post by Mr. Jon Donnis on Jul 14, 2009 17:45:03 GMT
Let’s say you work in a Post Office and a woman comes in to claim her child benefit for her 2 children. You notice that she has one child with her – a boy. With this information, would you conclude that her other child is more likely to be another boy, a girl, or can’t you tell? What level of confidence do you have in your answer (i.e. what’s the probability that you’re right)? I would say a girl, and be 50% confident in my answer  |
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Post by fluffet on Jul 14, 2009 17:57:02 GMT
50/50....just because she already has a boy doesnt change that there are only two options possible.
You would still have a 50/50 chance of being right.
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Post by fluffet on Jul 14, 2009 17:58:25 GMT
Plus how do you even know the child with her is hers anyway ,could be the neighbours.
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Post by theminx on Jul 14, 2009 18:47:29 GMT
The lady could be collecting child Benefit for someone else?
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Post by tomroberts on Jul 14, 2009 21:35:15 GMT
Well, I'll give it a go - probably wrong, but assuming it is not a trick question, and taking into account what fluffet and minx said, I would be fairly certain there is no way of knowing. I'm sure jigsaw will delight in telling me I'm wrong.  Must take more clever pills. ;D |
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Post by fluffet on Jul 14, 2009 22:08:50 GMT
Never having claimed child benefit im not sure if this is the case or not but perhaps someone can clear it up for me .
If you worked in the post office you would see the child benefit book the mother presented when she arrived .Does that have the names of the children being claimed for on it ?
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Post by fluffet on Jul 14, 2009 22:21:49 GMT
Of course if we are only to conclude from the information stated alone in the question posed above and arent allowed more information then if we have to make a choice it would merely be a guess which we would have a 50/50 chance of getting right.
The only definate choice to make with 100% certainty it was the right one is that you couldnt conclude any answer from that information that would be guarantee your certainty of the sex.
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Post by asdfg on Jul 15, 2009 9:27:16 GMT
No right answers yet..... |
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Post by The Legendary Barb on Jul 15, 2009 10:03:57 GMT
If you knew the woman in question, that she may be a relative your daughter / inlaw for instance you would know your grandchildren.
The woman could also be your wife ,a close friend or neighbour.
You could be then 100% right.
Fluffet in days gone bye the childrens names were not on the book.
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Post by blackadder on Jul 15, 2009 11:40:41 GMT
I'd ask her. |
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Post by muppet on Jul 15, 2009 11:41:54 GMT
I would just assume that the other child is in school |
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Post by muppet on Jul 15, 2009 11:43:03 GMT
In fact, can you still claim that at a post office now? I thought it was all done by direct debit...I suppose there are people with no bank account, just few and far between.  |
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Post by asdfg on Jul 15, 2009 12:43:13 GMT
OK, I'll reframe it a bit.
There are 4 ways of having 2 children and if we take a sample of 120 women who have 2 children the distribution would go like this (assuming no variance):
[Boy - Boy] n=30
[Boy - Girl] n=30
[Girl - Boy] n=30
[Girl - Girl] n=30
In the original question we know that a woman has 2 children at least one of which is a boy, so using the distribution above, what is the likelihood (or probability) that the other child is a girl?
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Post by bobdezon on Jul 15, 2009 15:27:25 GMT
1/3
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Post by asdfg on Jul 15, 2009 15:35:33 GMT
Right lines but wrong answer Bob! ;D
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Post by tomroberts on Jul 15, 2009 15:49:19 GMT
Twice as likely to be a girl than a boy?
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Post by asdfg on Jul 15, 2009 17:02:36 GMT
Twice as likely to be a girl than a boy? Yeay! Gold star for Tom. ;D |
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Post by bobdezon on Jul 15, 2009 18:13:13 GMT
Well, at first I thought it was a variation on the theme of the Monty Hall problem. en.wikipedia.org/wiki/Monty_Hall_problemI have since found out it is actually called the boy/girl paradox (nothing to do with trannies oddly enough) en.wikipedia.org/wiki/Boy_or_Girl_paradoxThe answer is dependant on the ambiguity of the question posed, as the intuitive answer is 1/2 but depending on circumstance it can also be 1/3 and this is why there has been so much debate about the "final answer". To be honest, on the surface, my sceptical "spidey sense" is pointing at the very noticable "changing the goalposts" to get a different answer. |
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