/sci/ - Science & Math » Thread #12369852

107KiB, 1024x683, 0_5jSRWOQDpdedf6kw.jpg

View Same Google iqdb SauceNAO

Anonymous Sat 21 Nov 13:47:14 2020 No.12369852 View Reply Original Report

Quoted By: >>12369859 >>12369861 >>12369877 >>12370002 >>12370014 >>12370080 >>12370407

1: A man has two children, one of which is a boy. What are the odds that the other child is also a boy?
2: A man has two children, and the older one is a boy. What are the odds that the other child is also a boy?

Anonymous

Anonymous Sat 21 Nov 2020 13:50:51 No.12369857 Report

Quoted By:

Uh sweaty, gender/sex is a spectrum. Girls and boys don't exist.

Anonymous

Anonymous Sat 21 Nov 2020 13:52:34 No.12369859 Report

Quoted By: >>12369862 >>12370002

>>12369852
>1: A man has two children, one of which is a boy. What are the odds that the other child is also a boy?
1/2

>2: A man has two children, and the older one is a boy. What are the odds that the other child is also a boy?
1/2

Anonymous

Anonymous Sat 21 Nov 2020 13:53:42 No.12369861 Report

Quoted By: >>12369866

>>12369852
Isn't it 1/3 for both?

Anonymous

Anonymous Sat 21 Nov 2020 13:53:52 No.12369862 Report

Quoted By: >>12369870

>>12369859
Incorrect

Anonymous

Anonymous Sat 21 Nov 2020 13:54:54 No.12369866 Report

Quoted By: >>12369867

>>12369861
Also incorrect

Anonymous

Anonymous Sat 21 Nov 2020 13:56:30 No.12369867 Report

Quoted By:

>>12369866
Oh yeah, it's 1/3 for question one and 1/2 for question two.

Anonymous

Anonymous Sat 21 Nov 2020 13:59:14 No.12369870 Report

Quoted By: >>12369874 >>12369876 >>12369882 >>12369910 >>12370013

>>12369862
Nope, it's correct. Since both questions refer to "the other child," the first part of both questions refers to a specific child, not the state of the pair. The genders of each child are independent from each other.

If you had asked about the pair instead of "the other child," then the question would be ambiguous.

Anonymous

Anonymous Sat 21 Nov 2020 13:59:54 No.12369872 Report

Quoted By: >>12370019

is this like a retarded version of the monty hall problem?

Anonymous

Anonymous Sat 21 Nov 2020 14:01:52 No.12369874 Report

Quoted By:

>>12369870
Elementary probability problems are so stupid. The only challenge is divining the actual meaning of the question and then all the calculation is trivial. Just give me a rigorously-defined probability space and ask something interesting.

Anonymous

Anonymous Sat 21 Nov 2020 14:02:08 No.12369876 Report

Quoted By: >>12369885

>>12369870
Fuck, I messed it up. Well, it's a retarded paradox anyway and I don't get it

Anonymous

Anonymous Sat 21 Nov 2020 14:02:11 No.12369877 Report

Quoted By: >>12369926

>>12369852
You are a biologist traveling through a rainforest when you are bitten by a venomous snake. Luckily the antidote to this venom is secreted on the back of the male of a certain species of frog native to this rainforest. You know females and males exist in equal proportion, socialize with each other randomly, and are indistinguishable aside from the fact that females croak randomly but males never croak. Amazingly, you see a frog of this species sitting silently in front of you. You then hear a croak and turn around to see a pair of these frogs where the croak came from. Knowing that you only have enough time to run to the lone frog to lick its back or to the pair to lick both their backs, which direction do you run and what is your chance of survival?

Anonymous

Anonymous Sat 21 Nov 2020 14:03:55 No.12369882 Report

Quoted By: >>12369888

>>12369870
Isn't "the other child" the exact same thing as the state of the pair? They refer to the same thing, no?

Anonymous

Anonymous Sat 21 Nov 2020 14:04:48 No.12369885 Report

Quoted By: >>12369892

>>12369876
It's pretty simple. If you only saw one child and it was a boy then you have information about a specific child and the gender of the other child is independent from that info. If your friend told you he saw both children and at least one is a boy then you have information about the pair, not a specific child, and the gender of both children is not independent from that info.

Anonymous

Anonymous Sat 21 Nov 2020 14:05:51 No.12369888 Report

Quoted By: >>12369895

>>12369882
>Isn't "the other child" the exact same thing as the state of the pair?
No, because you can get information about the pair that doesn't refer to a specific child.

Anonymous

Anonymous Sat 21 Nov 2020 14:06:47 No.12369892 Report

Quoted By: >>12369898 >>12370030

>>12369885
How is the gender of the other child not independent from that info? If you flip a coin and it lands on heads then the probability of ut landing on heads again is still 1/2

Anonymous

Anonymous Sat 21 Nov 2020 14:07:48 No.12369895 Report

Quoted By: >>12369901

>>12369888
No more info is given, you know that it's a pair in both cases

Anonymous

Anonymous Sat 21 Nov 2020 14:09:19 No.12369898 Report

Quoted By: >>12369900

>>12369892
>How is the gender of the other child not independent from that info?
What "other child?" In order for "other child" to make sense, the information would have to refer to a specific child in the first place.

If I flip two coins and tell you I counted the number of heads and it's greater than 0, does this tell you anything about a specific coin? No.

Anonymous

Anonymous Sat 21 Nov 2020 14:10:29 No.12369900 Report

Quoted By: >>12369904

>>12369898
I don't get it

Anonymous

Anonymous Sat 21 Nov 2020 14:11:19 No.12369901 Report

Quoted By: >>12369906

>>12369895
The information that was given in the hypothetical I'm talking about doesn't refer to a specific child, it only refers to the state of the pair. I'm not adding information.

Anonymous

Anonymous Sat 21 Nov 2020 14:12:21 No.12369904 Report

Quoted By:

>>12369900
Which child is the other child?

Anonymous

Anonymous Sat 21 Nov 2020 14:13:03 No.12369906 Report

Quoted By: >>12369910

>>12369901
If you're not adding information, how can the probability change? The answer is supposed to be 1/3 for the first one and 1/2 for the second one

Anonymous

Anonymous Sat 21 Nov 2020 14:17:22 No.12369910 Report

Quoted By:

>>12369906
>If you're not adding information, how can the probability change?
I'm taking away information.

>The answer is supposed to be 1/3 for the first one
No, it's worded incorrectly. See >>12369870

Anonymous

Anonymous Sat 21 Nov 2020 14:28:50 No.12369926 Report

Quoted By: >>12369943

>>12369877
The pair, as it gives 2/3 odds, since there are 4 possible "states" for a pair of frogs (both male, both female, and 2 ways to order them if of different sexes), with one state (both male) eliminated due to the croak. Is this right, or am I retard?
Trick question: I'm a retard for entertaining this thought experiment.

Anonymous

Anonymous Sat 21 Nov 2020 14:32:30 No.12369939 Report

Quoted By:

Let's try explaining this a different way. Here are all the states a pair of children can be in, all equally likely:

BB
BG
GB
GG

The distinction between information about a specific child and information only about the pair is simply saying that BB is 1/2 of the states where a specific column is B and 1/3 of the cases where either column is B.

Anonymous

Anonymous Sat 21 Nov 2020 14:35:08 No.12369943 Report

Quoted By:

>>12369926
>The pair, as it gives 2/3 odds, since there are 4 possible "states" for a pair of frogs (both male, both female, and 2 ways to order them if of different sexes), with one state (both male) eliminated due to the croak.
Incorrect. You're ignoring that we heard a frog croak. So the states are actually

Fc F
Fc M
M Fc
F Fc

You know how to apply the logic of the boy girl paradox but don't truly understand when it applies.

Anonymous

View Same Google iqdb SauceNAO 1597987911581.jpg, 216KiB, 1908x1146

Anonymous Sat 21 Nov 2020 14:42:41 No.12369961 Report

Quoted By:

>this thread

Anonymous

Anonymous Sat 21 Nov 2020 15:03:15 No.12370002 Report

Quoted By: >>12370013

>>12369852 (OP)
>>12369859
>1: A man has two children, one of which is a boy. What are the odds that the other child is also a boy?
2/3

>2: A man has two children, and the older one is a boy. What are the odds that the other child is also a boy?
1/2

Anonymous

Anonymous Sat 21 Nov 2020 15:07:13 No.12370013 Report

Quoted By: >>12370104

>>12370002
>2/3
Incorrect. See >>12369870

Anonymous

Anonymous Sat 21 Nov 2020 15:07:22 No.12370014 Report

Quoted By:

>>12369852
>assuming there are only two genders
>assuming boy/girl are 50-50
>assuming there's no correlation between sibling genders

Anonymous

Anonymous Sat 21 Nov 2020 15:08:16 No.12370019 Report

Quoted By: >>12370048

>>12369872
Yes, it's another way to misstate the Monty Hall problem so people get the "incorrect" answer. Not sure if OP is doing it to trip people up so he can feel intellectually superior or if he's simply an idiot.

Anonymous

Anonymous Sat 21 Nov 2020 15:13:01 No.12370030 Report

Quoted By:

>>12369892
no. a woman is more likely to have same gender kids.

also, since there is no fair coins, if a coin lands on head, a better guess would be it'll land on head again. if a coin lands on heads 10 times in a row, only a statistician would bet on tail next time - because... theory?

Anonymous

View Same Google iqdb SauceNAO 8d6.jpg, 48KiB, 645x729

Anonymous Sat 21 Nov 2020 15:16:25 No.12370048 Report

Quoted By:

>>12370019
>Every probability question is Monty Hall

Anonymous

Anonymous Sat 21 Nov 2020 15:26:51 No.12370080 Report

Quoted By: >>12370112

>>12369852
0%, both questions state that only one is a boy

Anonymous

Anonymous Sat 21 Nov 2020 15:36:44 No.12370104 Report

Quoted By: >>12370107

>>12370013
"One of which" is not specific. "The older one" is.

Anonymous

Anonymous Sat 21 Nov 2020 15:38:23 No.12370107 Report

Quoted By: >>12370118

>>12370104
>"One of which" is not specific.
It is if it's followed up by a question about "the other child."

Anonymous

Anonymous Sat 21 Nov 2020 15:39:25 No.12370112 Report

Quoted By:

>>12370080
Neither say that.

Anonymous

Anonymous Sat 21 Nov 2020 15:41:16 No.12370118 Report

Quoted By: >>12370148

>>12370107
No it isnt. You still dont know if hes talking about child 1 or 2.

Anonymous

Anonymous Sat 21 Nov 2020 15:56:27 No.12370148 Report

Quoted By: >>12370271

>>12370118
If he's taking about 2 children then he can't ask about "the other child."

Anonymous

Anonymous Sat 21 Nov 2020 16:39:01 No.12370271 Report

Quoted By: >>12370312

>>12370148
>If he's taking about 2 children then he can't ask about "the other child."
Hes talking about 1 out of 2 kids. Not 2 kids. And we dont know which kid hes talking about so we take both kids into consideration when calculating the probability.

Anonymous

Anonymous Sat 21 Nov 2020 16:52:28 No.12370312 Report

Quoted By: >>12370342

>>12370271
>Hes talking about 1 out of 2 kids.
Yes, so a specific kid.

>And we dont know which kid hes talking about
It doesn't matter which kid he's talking about since the question is about the other kid.

>so we take both kids into consideration when calculating the probability.
It doesn't matter if you take both kids into account, the gender of the other kid is independent from the first one.

Anonymous

Anonymous Sat 21 Nov 2020 17:04:24 No.12370341 Report

Quoted By: >>12370385

>1: 1/3
BB, BG, GB, GG
Given there must be at least one boy GG is eliminated so
BB, BG, GB
where the outcome of both-boys is BB is 1/3.

>2: 1/2
BB, BG, GB, GG
First chid is B, so GB and GG eliminated so
BB, BG
where the outcome of both boys BB is 1/2.

Anonymous

Anonymous Sat 21 Nov 2020 17:04:46 No.12370342 Report

Quoted By: >>12370398

>>12370312
We dont know if hes talking about the older or younger child so how is it a specific child? Saying the other one still wont specify which child it is hes talking about.

Anonymous

Anonymous Sat 21 Nov 2020 17:13:21 No.12370385 Report

Quoted By:

>>12370341
>Given there must be at least one boy GG is eliminated
The question asks about "the other child" so the states are simply

BB
BG

Anonymous

Anonymous Sat 21 Nov 2020 17:16:14 No.12370398 Report

Quoted By:

>>12370342
>We dont know if hes talking about the older or younger child so how is it a specific child?
Huh? Why would it matter which one is younger or older? We know it's a specific child because he says "the other child." I don't know why you keep failing to respond to this. You are confusing the question being about a specific child with the question telling us which child is which in relation to some trait. The trait is not relevant, only specificity is.

Anonymous

Anonymous Sat 21 Nov 2020 17:18:01 No.12370407 Report

Quoted By:

>>12369852
zero bc i'd abort if it was a girl.

Capcode	All Only User Posts Only Moderator Posts Only Admin Posts Only Developer Posts
Show Posts	All Only With Images Only Without Images
Deleted Posts	All Only Deleted Posts Only Non-Deleted Posts
Ghost Posts	All Only Ghost Posts Only Non-Ghost Posts
Post Type	All Only Sticky Threads Only Opening Posts Only Reply Posts
Results	All Grouped By Threads
Order	Latest Posts First Oldest Posts First

Your latest searches