A simple logic problem

[djmatt]

I think 16 pages of this really shows that books are doing well.. if people dont understand probability how is it possible to be successful long term gambling

 

[quantumleap]

what if my aunt had balls?

Then she would be your uncle.

 

[GoForBroke]

I know, and this is a gambling forum. We trust ourselves to make determinations between microscopic magnitudes of value, and yet 14 pages of explanations don't convince people. Makes me slightly uneasy...

Timotinbowen's post sums it up.

Okay I can understand people coming to the conclusion 50% is the correct answer. Whether it's because you read the question incorrectly or you're just an idiot. But if proof has been displayed more or less every page from the start, how can you deny that? A few changed their answer to 66.7% after seeing the proof, yet we still have some who can't accept it.

For all the 50% people, are you implying what our teachers are teaching is bogus? Give me a fucking break, this isn't rocket science.

 

[Biggamer3]

Wow first off i thought it was 50 % for sure, but after seeing the reasons for the contrary i am now going with 66.66%

three options:
BB
BG
GB

= 2 out of 3 scenarios

 

[buddyboy]

BREAKING NEWS: The Sportsbooks that sponsor the Rx invite all those posters that answered 50% to open accounts with them.

To the posters that answered 2/3rds... your accounts will be considered wiseguy and closed asap.

INSANE

I foresee this thread being refered to on many a math forum as "logic problem stumps sportsbetting community"

:missingte

 

[Biggamer3]

Dont know if this was posted in 17 pages or not but this blog elaborates quiet a bit on this question and says the answer is 2/3

http://www.codinghorror.com/blog/archives/001204.html

 

[buddyboy]

girl -200
boy +200

 

[Kruser6]

I just want it to be explained why BG and GB should count as 2 scenarios and I'll be happy.

 

[festeringZit]

I just want it to be explained why BG and GB should count as 2 scenarios and I'll be happy.

It has been explained about 20 times over the last 16 pages.

Read through the thread.

 

[Biggamer3]

It has been explained about 20 times over the last 16 pages.

Read through the thread.

Zitty i think 2/3 is the correct answer, but how would you answer this question posed by someone from another board

How about this argument for 50/50. Lets replace the random "boy" with a name like Tom. Wouldn't it then be

Tom/boy
Tom/girl
boy/Tom
girl/Tom

 

[festeringZit]

Zitty i think 2/3 is the correct answer, but how would you answer this question posed by someone from another board

Once you identify one of the boys, by name or (for example) say "older son"
or "younger son" the answer is 50/50.

This also as been gone-over also in this thread about 20 times.

E.g.

A family has two children, the oldest child is a boy. What is a probability
the family has a daughter? 50/50

 

[RobFunk]

I think 16 pages of this really shows that books are doing well..

:lolBIG:

 

[Biggamer3]

Once you identify one of the boys, by name or (for example) say "older son"
or "younger son" the answer is 50/50.

This also as been gone-over also in this thread about 20 times.

E.g.

A family has two children, the oldest child is a boy. What is a probability
the family has a daughter? 50/50

I read a lot of this thread, never saw the subject of "name" change the answer.

Why exactly should giving the already said son a name of Tom really change the probability?

 

[festeringZit]

Zitty i think 2/3 is the correct answer, but how would you answer this question posed by someone from another board

Looking at this some more, it depends how the question is worded.

 

[buddyboy]

everyone knows that

1+2=3

and

2+1=3

so

2+1 = 1+2

or

3 = 3

sounds like all the people thinking 50% are assuming:

boy + girl = all the mans children

girl + boy = all the mans children

when they should be looking at it like:

all the mans children = first born child + second born child = 2 children

just like:

all the flips of a coin = first flip = one flip

or

all the flips of a coin = first flip + second flip = two flips

is this getting clearer?

 

[CapNCash]

The thing that I dont understand is how can you have:

BG Where boy is older

AND

GB where girl is older

but you cant have

B1B2 where boy one is older

AND

B2B1 where boy 2 is older

Why does the older and younger boy not get factored (B1B2) when there are 2 boys but it does get factored in when you have a boy and a girl (GB and BG)?

I think the argument for the 50%ers is that if you are going to factor in BG and GB then you should factor in BB(1) and BB(2)?

 

[Biggamer3]

The thing that I dont understand is how can you have:

BG Where boy is older

AND

GB where girl is older

but you cant have

B1B2 where boy one is older

AND

B2B1 where boy 2 is older

Why does the older and younger boy not get factored (B1B2) when there are 2 boys but it does get factored in when you have a boy and a girl (GB and BG)?

I think the argument for the 50%ers is that if you are going to factor in BG and GB then you should factor in BB(1) and BB(2)?

Yep thats why the "Tom" question stumped me.

It looks like all the experts say its 66.67% but 50/50 makes more sense to me now

 

[CapNCash]

Wow first off i thought it was 50 % for sure, but after seeing the reasons for the contrary i am now going with 66.66%

three options:
BB
BG
GB

= 2 out of 3 scenarios

but you are assuming the age matters if it is boy and girl but doesnt matter if it is boy/boy. why?

why not?

BB(1)
BB(2)
GB
BG

 

[festeringZit]

The thing that I dont understand is how can you have:

BG Where boy is older

AND

GB where girl is older

but you cant have

B1B2 where boy one is older

AND

B2B1 where boy 2 is older

Why does the older and younger boy not get factored (B1B2) when there are 2 boys but it does get factored in when you have a boy and a girl (GB and BG)?

I think the argument for the 50%ers is that if you are going to factor in BG and GB then you should factor in BB(1) and BB(2)?

A family has two kids, there are 4 options:

BG
GB
BB
GG

There are not two options for BB, there are not two options for GG.

In the original problem, we are only able to rule out GG. That leaves
three options:

BG 1/3
GB 1/3
BB 1/3

 

[CapNCash]

but if age doesnt matter there are only 3 possible combinations:

BB
GG
GB or GB

Why does GB or BG matter? I know im wrong i just dont understand why?

You either have:

2 boys
2 girls
1 boy and 1 girl