A simple logic problem

[Geoff101]

You are given B1's existence. Therefore, B2, G is not a possibility. Further, we are only looking at permutations of the set. So {B1, B2}, {B1, G1}, {B1, G2} are the possibilities.

Do you still really believe that you'd get rich off the earlier wager? Even after seeing the "100 parents in a room" example, all other evidence, and the knowledge that this is an elementary set theory problem?

absolutely...I know that I would take you for a bundle...

 

[festeringZit]

absolutely...I know that I would take you for a bundle...

This guy Geoff is either:

1. insane
2. dumb as a box of rocks
3. just trolling to be a prick

 

[festeringZit]

Probability is infinite. It has no 'hard' mathematical value nor does it have an absolute.

In the example given, you can only solve for the chances of what is 'probable'.

I guarantee you this is spoken by someone who has little or no
formal training in mathematics.

 

[GoForBroke]

14 pages later... we still have people believing the answer is 50% hno:

 

[timotinbowen]

In your example, you know the outcomes as they happen (the order). I skipped pages 5-12, so I don't know if it has been explained this way:

100 fathers in a room.
25 have GG
25 have BB
50 have BG

Everyone without a B is told to leave. You have 75 fathers left:
25 have BB
50 have BG

So of the fathers who have at least one B (75), 50 have a girl. 50/75 = 2/3.

Geoff, where is this wrong?
LOL at making a bundle. So you are saying that all mathematical models outlined in this thread are wrong? All college professors that open introductory statistics courses with this problem are wrong? Bayes' Theorem is wrong?

Do the example with 2 coins!! Do it 1000 times, and you can solidify or change your mind. It will take 20 minutes. Also, look at some of these articles (perhaps they can explain it better than I can):
http://www.tanyakhovanova.com/Puzzles/
http://members.cox.net/srice1/random/probprdx.html
http://books.google.com/books?id=Gw...&hl=en&sa=X&oi=book_result&resnum=2&ct=result
http://dev.whydomath.org/Reading_Room_Material/ian_stewart/9609.html

This is a classic probability paradox! I am a math major, and I had fun with these types of problems in early stats classes. This is not advanced mathematics, and you are incorrect.

 

[buddyboy]

labeling this thread 'simple logic problem' lol

math can be difficult when the wrong answer seems to be logical.

if you have conflicting answers it's because someone has identified the problem incorrectly.

a man with two kids, one is male. is the other male or female?

what about:?

a man with three kids, one is male, how many brothers or sisters?

a man flips a coin 2 times, one time is heads....

hno:

 

[timotinbowen]

14 pages later... we still have people believing the answer is 50% hno:

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...

 

[steaktartar]

66.7% CHANCE a girl

 

[GoForBroke]

 

[quantumleap]

nope...B2 is absolutely an option...you can certainly have 2 boys per the puzzle B1 and B2, and you can have B2 an B1, just as you can have B1 and G and G and B1

B2 is an option but tim was not taking the boy or the girl option separately. He was talking about sets, not individuals as he replied to your 4 options of sets. The set of B2 & G is not an option as you have it listed as 1 of your options.

Therefore you have 3 sets of options left.

 

[$tinky]

The fact that this thread has 14 pages is ridiculous.

 

[Doug]

¡ sǝƃɐd 51 ʇɐɥʇ ǝʞɐɯ

 

[Cubsmac]

An equivalent and perhaps clearer way of stating the problem is "Excluding the case of two girls, what is the probability that two random children are of different gender?"

Anybody argue that the answer is not 2/3rds???

 

[JaBrady]

Geoff - why dont you make a list of all family/friends/etc of yours that have exactly 2 children with 1 being a male. Report back your results.

 

[AlwayzRight]

Wow some of you people THINK WAY to hard about things.

He has 2 kids, one is a boy, so the other is a boy or girl(50-50)...wow people. How the fuck did this reach 15 pages?

 

[fhmesq44]

An equivalent and perhaps clearer way of stating the problem is "Excluding the case of two girls, what is the probability that two random children are of different gender?"

Anybody argue that the answer is not 2/3rds???

Illini did at first, but he realized why the answer is 2/3. Geoff was asked that question a couple of times but never answered.

 

[fhmesq44]

Geoff - why dont you make a list of all family/friends/etc of yours that have exactly 2 children with 1 being a male. Report back your results.

I actually did this last night, so I will start, add yours to the tally:

Boy/Boy 23
Boy/Girl 36

 

[CapNCash]

Wow some of you people THINK WAY to hard about things.

He has 2 kids, one is a boy, so the other is a boy or girl(50-50)...wow people. How the fuck did this reach 15 pages?

it is not 50-50 that is the issue

 

[festeringZit]

Wow some of you people THINK WAY to hard about things.

He has 2 kids, one is a boy, so the other is a boy or girl(50-50)...wow people. How the fuck did this reach 15 pages?

You need to change your name from AlwayZRight to NotRightThisTime

 

[JaBrady]

I actually did this last night, so I will start, add yours to the tally:

Boy/Boy 23
Boy/Girl 36

just did it with everyone in my phone

B/B 11
B/G 20