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/sci/ - Science & Math


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12418876 No.12418876 [Reply] [Original]

There are 3 possible scenarios:
1. There are 2 heads coins
2. There is a heads coin and a tails coin
3. There are 2 tails coins
Next we eliminate those which dont fit the criteria of having "at least one coin is heads" and we are left with:
1. There are 2 heads coins
OR
2. There is a heads coin and a tails coin
The question does not give any information regarding order of the coins, therefore there is no "first" or "second" coin, there are only the sets which contain either 2 heads or a heads and a tails.
Probability= favourable outcomes/possible outcomes
Without the criteria of "at least one is heads" there would be 3 possible outcomes, and a 1/3 chance of both being heads, but after applying that criteria, it becomes impossible to land two tails coins. Thus we are left with one favourable outcome (both coins are heads) and two possible outcomes (both are heads OR one heads and one tails)
The probability of both coins being heads is 1/2

>> No.12418883

Is this your or Bob’s opinion?

>> No.12418889

>>12418876
Are you mentally ill?

>> No.12418908

>>12418876
Couldn't this be found out empirically with a few hundred coin tosses?

>> No.12418909

>>12418876
Two coins [math]\Rightarrow [/math] two random variables.
The coins are indexed. Probability is 1/3.

>> No.12418931

>>12418909
Without any information about the distribution, we should assume a flat prior. Thus two heads is as likely as a head and tails. This is standard textbook probability theory.

>> No.12418936

>>12418909
>Two coins two random variables
two random variables that will randomly land on scenarios within the bounds of the criteria.
>Probability is 1/3.
Show me 3 possible outcomes that fit the criteria of "at least one is heads"

>> No.12418940

>>12418936
HH, HT, TH

>> No.12418947

>>12418940
HT and TH are both exactly the same, as they both contain one heads coin and one tails coin. there is no first or second coin and the problem gives no information about the order of the coins. They are both one heads and one tails

>> No.12418962

>>12418947
Any two coins are distinguishable. The random variables corresponding to each coin are therefore independent. Therefore, HT and TH are distinct.
Alternatively, if you wish to HT and TH as identical, then HT \mapsto 1/2, while HH \mapsto 1/4, and TT \mapsto 1/4. After removing TT and normalizing, you see that HT \mapsto 2/3 and HH \mapsto 1/3.

>> No.12418974

>>12418962
You're forgetting that two heads makes it twice as likely that "at least one is heads" is given as information. So HH is as likely as HT or TH and the answer remains 1/2.

>> No.12418976

>>12418947
you flip two coins. what is the probability that both are head?

>> No.12418983

>>12418931
>Without any information about the distribution, we should assume a flat prior.
that's clearly wrong, heuristically

>> No.12418987

>>12418974
>You're forgetting that two heads makes it twice as likely that "at least one is heads" is given as information
Prove it then.

>> No.12418991

>>12418962
>HT \mapsto 1/2, while HH \mapsto 1/4, and TT \mapsto 1/4. After removing TT and normalizing, you see that HT \mapsto 2/3 and HH \mapsto 1/3.
if it is the case that any two coins are distinguishable then i can just as easily say that h refers to a second heads coin (if present in the set) and divide HH into Hh and hH to distinguish them, bringing the probability back to 1/2
These things will only matter if the coins are flipped one after the other and there is a first and second coin, which the problem didnt specify.

>> No.12418994

>>12418983
How so?

>> No.12418995

>come to /sci/ to see what it's like
>they're arguing over 5th grade math

>> No.12418996

>>12418994
flip two coins several times. you will see that HT occurs more frequently than HH.

>> No.12418997

>>12418991
No, because in that case H is in the domain of the first random variable but not the second random variable, while h is in the domain of the second random variable but not the first random variable, so only one of Hh or hH is an outcome of the system.

>> No.12418998

>>12418987
the probability of one of the coins being heads is 100% if we look at them as separate entities. If this wasnt true, then getting TT would be a possibility, which it isnt.

>> No.12419001

>>12418987
Sure. Since coins are distinguishable there are four coins that can be given as heads:

1. two heads are tossed, left coin is given as "at least one is heads"

2. two heads are tossed, right coin is given as "at least one is heads"

3. Right coin is heads and left is tails

4. Left coin is heads and right is tails

Half of the time "at least one is heads" both are heads.

>> No.12419002

>>12418908
every time this thread pops up, a different anon codes a script and shows that the probability converges to 1/3. Trolls will never ever stop posting this shit though, it's a /sci/ meme.

>> No.12419005
File: 214 KB, 1280x1024, 1137646805113.jpg [View same] [iqdb] [saucenao] [google]
12419005

LMFAO YES!
In this thread "boy girl" schizo foams at the mouth for 500 comments about a wikipedia psychoanalysis of ambiguous language, and how it is somehow related to the unambiguous language in the OP question.

Boy girl schizo unfortunately loses 0-500 yet again, but the award for best supporting actor will almost certain be won by his imaginary friend, Bob.

>> No.12419006

>>12418996
Which coins though? The distribution is unknown.

>> No.12419009

>>12419001
>left coin is given as "at least one is heads"
>right coin is given as "at least one is heads"
Never happens.

>> No.12419010

>>12419001
you're assuming that a specific coin is given as heads. that's not what the problem says. it's an information about both coins which cannot be reduced to an information about a single coin.

>> No.12419017

>>12418996
>>12419002
Yes that is true because in the real world there will always be a first and second coin, and the probability would definitely be 1/3. The problem however doesnt mark any coin as "coin 1" or "coin 2", so changing the order of the coins doesnt change what is contained in the set. Without marking the coins, show me 3 possible outcomes other than two heads and one heads one tails

>> No.12419026

>>12419006
This exactly.
You cannot say that TH and HT are distinguished from one another and HH is one result when HH consists of 2 different distinguished random entities.

>> No.12419028

>>12419017
it doesn't matter if you work with ordered or unordered coin tosses.

with ordered tosses, the sample space is {HH,TH,HT,TT} with uniform distribution.

with unordered tosses, the sample space is {HH,TH,TT} where the distribution is

P(TH) = 1/2
P(HH) = P(TT) = 1/4

probability of both heads with the assumption that TT cannot occur is 1/3 in both cases.

>> No.12419029

>>12419017
>show me 3 possible outcomes
There aren't, and one each happens twice as often.
x + 2x = 1
3x = 1
x = 1/3
HH = 1/3
HT = 2/3
ezpz

>> No.12419030

>>12419017

import scipy.stats

I = 100000 # number of tosses

Tosses_with_at_least_one_head = 0
Tosses_with_both_heads = 0

for k in range(0,I):
toss = scipy.stats.bernoulli.rvs(size=2,p=1/2)
if sum(toss) >= 1:
Tosses_with_at_least_one_head += 1
if sum(toss) == 2:
Tosses_with_both_heads +=1

P = Tosses_with_both_heads/Tosses_with_at_least_one_head
print(P)

this script does not index the coins. It converges to 1/3

>> No.12419034

>>12419026
>HH is one result when HH consists of 2 different distinguished random entities.
now you're just being retarded on purpose

>> No.12419037

>>12419017
If you toss two coins HH will show 1/4 of times, HT 2/4 and TT 1/4. If you remove TT you are left with HH 1/4 and HT 2/4.

>> No.12419039

>>12419001
This is the most nonsensical argument I've ever seen on this topic.

>> No.12419050
File: 100 KB, 700x70, output_2.webm [View same] [iqdb] [saucenao] [google]
12419050

Why are we even talking about this

>> No.12419058

>>12419028
>>12419029
>>12419030
>>12419034
>>12419037
I accept defeat, and i concede that the probability is in fact 1/3, thank you for opening my eyes.

>> No.12419059

>>12419050
>Why are we even talking about this
some people are hallucinating

>> No.12419063

>>12419039
If you think that's good, just wait for the follow-up argument, which constructs an imaginary friend Bob, who can then enter the question in order to "observe" and "know" specific coins, and then relay that knowledge back to the test taker.

>> No.12419071

>>12419009
So the answer is 0?

>> No.12419076

>>12419071
Neither the left nor the right coin are ever given as heads.

>> No.12419079

>>12419010
>you're assuming that a specific coin is given as heads.
Please explain how "at least one is heads" doesn't mean a coin is heads.

>it's an information about both coins
No, it's information about one. Assuming it's information about both is adding information not given and fails to treat the coins as distinguishable objects.

>> No.12419080

>>12418876
>your head is a coin
>on both sides, what is the chance that this happens

>> No.12419086

>>12419039
Do you have an actual argument against it?

>> No.12419091

>>12419079
>Please explain how "at least one is heads" doesn't mean a coin is heads.
Read the question, it refers to the result of two coin flips, not to one coin.

>> No.12419095

>>12419079
>No, it's information about one.
Did Bob tell you that? I couldn't find it in the OP

>> No.12419097

>>12419076
It's not clear what you mean. Do you mean it's not specified whether the coin referred to is the left or right coin? That has no bearing on my argument since it allows either coin to be the one referred to. Do you mean neither coin is heads? Then how is at least one heads?

>> No.12419099

>>12419086
>left coin is given as "at least one is heads"
>right coin is given as "at least one is heads"
This doesn't even make sense in the context of the question. The condition is just that "at least one coin is heads". Also, this condition that at least one coin is heads does not change the fact that the probability of one heads and one tails is twice that of the probability that both coins are heads.

>> No.12419100

>>12419079
consider [math](x_1,y_2) \in \mathbb{R}^2[/math]. is "at least one coordinate is non-zero" information about both coordinates, or can it be reduced to an information about a single coordinate?

>> No.12419101

>>12419097
There is no coin that is ever "the one referred to."

>> No.12419107

>>12419091
That doesn't follow. "At least one is heads" refers to "one" coin, among two.

>> No.12419120

>>12419107
No. It is a statement about the system (which involves two coins). Labeling the coins A and B, we see that the statement "there is at least one heads" depends on the state of both A and B. Why? If A is not heads, then the statement depends on the state of B. On the other hand, if B is not heads, then the statement depends on A. Therefore, the statement "there is at least one heads" cannot be fully determined by looking at the outcome of only one of the coins.

>> No.12419121

>>12419095
>at least one is heads

>> No.12419123

>>12419107
No, the second clause in the sentence refers directly to the first clause, not to something else.

>> No.12419132

>>12419121
>at least one [ref. "You flip two coins"] is heads

>> No.12419133

>>12419099
>The condition is just that "at least one coin is heads"
Right, which means one coin is heads. Either the left coin or the right coin. It's not that hard, you'll get it eventually.

>> No.12419135

>>12419107
no. it's an information about both coins. just because it uses the word "one" doesn't mean it's an information about a single coin.

>> No.12419141

>>12419133
>Either the left coin or the right coin.
Did Bob tell you this? I couldn't find it in the OP

>> No.12419144

>>12419101
>There is no coin that is ever "the one referred to."
So there is no coin that is heads? No, clearly that information is given.

>> No.12419146 [DELETED] 

>>12419144
One of the two coin flips resulted in heads.

>> No.12419152

>>12419120
>No. It is a statement about the system (which involves two coins).
Right, a statement about one coin is also a statement about the system.

>Labeling the coins A and B, we see that the statement "there is at least one heads" depends on the state of both A and B. Why? If A is not heads, then the statement depends on the state of B. On the other hand, if B is not heads, then the statement depends on A.
That's exactly what I showed here >>12419001. Do you have an actual point?

>Therefore, the statement "there is at least one heads" cannot be fully determined by looking at the outcome of only one of the coins.
Who is determining it or looking at the outcome? The information is given. Stop hallucinating, schizo.

>> No.12419153

>>12419144
There are two coin flips, which resulted in one or more heads.

>> No.12419156

>>12419152
>Who is determining it or looking at the outcome?
Bob is, apparently. The OP certainly isn't.

>> No.12419173

>>12419100
Clearly it's only telling you about one coordinate, not both. Saying it's about both is fake information you don't have. I'm not sure what you mean by "reduced" to since saying one coordinate is non-zero is already about a single coordinate.

>> No.12419179 [DELETED] 

>>12419173
>one coordinate is non-zero is already about a single coordinate
That statement refers to two coordinates, not to a single cooridnate.

>> No.12419184

>>12419123
Where did I say anything different? If course is referring to one coin among the pair previously referred to, not some other coin.

>> No.12419185

>>12419173
>saying one coordinate is non-zero is already about a single coordinate
That statement refers to two coordinates, not to a single coordinate.

>> No.12419189

>>12419173
>>12419173
consider [math](x_1,y_2) \in \mathbb{R}^2[/math]. is "[math]x^2+y^2 > 0[/math]" information about both coordinates, or can it be reduced to an information about a single coordinate?

>> No.12419192

>>12419132
And?

>> No.12419193

>>12419184
It's referring directly to two coin flips, not to one coin.

>> No.12419195

>>12419189
[math](x_1,y_2) = (x,y)[/math], my bad

>> No.12419198

>>12419192
The reference is to the first clause of the sentence, not to something else.

>> No.12419202

>>12419135
>it's an information about both coins.
>one is
not
>both are
Trying to stretch information about one coin to both coins is just making up fake information.

>> No.12419205

>>12419202
There is no information that refers to a single coin.

>> No.12419208

>>12419202
it already is an information about both coins

>> No.12419385
File: 48 KB, 469x547, 2020-11-30 (1).png [View same] [iqdb] [saucenao] [google]
12419385

>>12418908
>>12418931
>>12418987
>>12419006

>> No.12419388

>>12419058
Wow, some actual humility on /sci/, truly a sight to behold.
Very based anon

>> No.12419405

>>12419107
Can be said about two coins too.
X the number of coins that are heads
X = 2 -> X ≥ 1

https://mathworld.wolfram.com/AtLeastOne.html

>> No.12419406

>>12419385
Why'd you tag me? The result is 1/3, as I said.

>> No.12419416

>>12419202
Trying to reduce an unspecified number of coins to only one is just making up fake information.

>> No.12419418

>>12419406
meant to tag the dude you were tagging, all good anon

>> No.12419459

>>12419173
>I'm not sure what you mean by "reduced"
there's a predicate [math]P(x)[/math] defined for [math]x \in \mathbb{R}[/math] such that either

"at least one coordinate is non-zero" [math]\iff P(x_1)[/math]

or

"at least one coordinate is non-zero" [math]\iff P(x_2)[/math]

there isn't. "at least one coordinate is non-zero" depends on both coordinates, and therefore cannot be described as an information about a single coordinate. it's counter intuitive, but true nonetheless.

>> No.12419486

Jesus fucking christ you guys are retarded:

Hh
hH
Ht
tH

It’s 1/2 idiots

>> No.12419504

>>12419486
What do H,h and t correspond to? Last time I checked, a coin has two sides.

>> No.12419543

>>12419504
If you had any sentience you would understand that H is the coin that has already been determined to be heads. It is not surprising a malformed flourided clamped spaded sub-hominid as yourself would not draw any meaningful inference. Did you know coins can actually land neither heads or tails?

>> No.12419551

>>12419543
>the coin that has already been determined to be heads
>the coin
into the trash it goes

>> No.12419576

>>12419504
Looks like a coded message from Bob. Any cryptography experts in here?

>> No.12419850

>>12419153
Right, meaning one coin is heads.

>> No.12419853

>>12419185
No it refers to one coordinate being non-zero.

>> No.12419857

>>12419850
No, it means what it says. There are two coin flips, which resulted in one or more heads.

>> No.12419860 [DELETED] 

>>12419853
No, it also means what it says, not something else.

>> No.12419883

(X ≥ 1) = (X = 1) ∪ (X = 2)

>> No.12419934

>>12419853
No, that also means what it says, not something else.

>> No.12419946

>>12419853
It refers to a certain number of coins that are heads, a number that is not zero.

>> No.12420041

>>12419946
This is logically equivalent to saying
(A & (B V!B)) v (B & (A v !A))
By reduction
A v B
Really straightforward.

>> No.12420044

>>12420041
Cool, another coded message from Bob.

>> No.12420164
File: 880 KB, 745x817, 1490383170344.png [View same] [iqdb] [saucenao] [google]
12420164

Let's go boy girl schizo!
RAH ! RAH !! RAH !!!
Don't let me down, you worm brained retard, I paid good money for these tickets.
Hh hH Ht tH
hH
Ht
tH

>> No.12420173

OP is right. It’s 1/2.

>> No.12420178

>>12420173
YAAASSSS QUEEEEEN

>> No.12420223

>>12420041
>>12419883 hon hon hon tit croissant

>> No.12420263

>>12418931
>Without any information about the distribution
"You flip two coins" is that information.

Perhaps the wording is misleading. If you phrase it using the past tense, it's more obvious: "Of all trials where two coins are flipped and those trials where both coins come up tails are discarded, what fraction of the remaining trials are both heads." When it is worded like this, then the answer is obviously 1/3rd.

>> No.12420329

>>12420263
>"Of all trials where two coins are flipped and those trials where both coins come up tails are discarded, what fraction of the remaining trials are both heads."
I disagree. Your new wording is actually less clear than the original wording, which is not only perfectly clear, but also doesn't confuse the reader by taking the form of a run-on sentence, or by referring the reader to an unspecified number of trials, some of which are discarded.

But yes, the answers to both are obviously 1/3.

>> No.12420335

>>12418876
nobody thought about the second coin standing on it's edge

>> No.12420398

>>12420263
>Of all trials where two coins are flipped and those trials where both coins come up tails are discarded, what fraction of the remaining trials are both heads.
it's fun that we know an information about every pair in the remaining set of trials: at least of the coins is heads. and yet it doesn't imply that we know the value of only one coin in the pair, or that a coin has been "observed".

I wonder where will this take us.

>> No.12420422
File: 13 KB, 800x600, Cointism.png [View same] [iqdb] [saucenao] [google]
12420422

Is theres something im missing? is this bait? its 1/3.

each square has an equal chance (25%) of occurring. with TT removed the options are HT, TH, and HH. So 1/3.

>> No.12420427

>>12420422
>Is theres something im missing? is this bait?
welcome to the loony bin. people are legit hallucinating in this thread.

>> No.12420465

>>12420398
> I wonder where will this take us.
To a completely different problem, with a whole new multiverse of Bob clones who are all playing a game of thrones against themselves and the test taker.

>> No.12420953

>>12419405
Right, and how does that respond to anything I said?

>> No.12420955

>>12419198
Yeah, and?

>> No.12420968

>>12419189
Information about both.

>> No.12420974

>>12419193
Is referring to a coin flip in the pair being heads.

>> No.12420979

>>12419205
"At least one is heads"

>>12419208
No.

>> No.12420985

>>12419385
That's nice, now do the problem.

>> No.12420989

>>12419416
>Trying to reduce an unspecified number of coins
An unspecified number is not information, one coin being heads is information.

>> No.12420999

>>12419459
>"at least one coordinate is non-zero" depends on both coordinates
Depends on in what way? As in, you need to check both coins to determine whether it's true? That's competent irrelevant and backwards. We are already given the information that it's true.

>> No.12421004

>>12419857
>>>12419934
>No, it means what it says.
So you agree I'm right, good.

>> No.12421009

>>12419946
>It refers to a certain number of coins that are heads, a number that is not zero.
No, you're talking about coordinates, and a number that isn't zero is not the same thing as at least one.

>> No.12421023

>>12418876
get two coins, toss both at the same time, record if there are 1 head or 2. If there are 0 heads record nothing and flip again until you record either 1 head or 2. Do this 100 times and tell us how many times there are 2 heads. Maybe then you can stop making this thread you utter fucking moron.

>> No.12421037

>>12420263
>"You flip two coins" is that information.
Sure, but not about the distribution of two coin flips.

>Of all trials where two coins are flipped and those trials where both coins come up tails are discarded
Incorrect, it should be of all coins where a head is observed, how many are part of a pair of heads. It's very simple.

>> No.12421158

This is not true. Let's say that you clip the coins simultaneously and they land a foot apart. You can only view one at a time. You know that each individual chance that it turns heads is 1/2.

The chance that it turns heads twice is 1/4, because no matter what these coins are not fluid and are separate entities. The number of possibilities is not 3, as the coins are independent entities and saying that one is heads and the other is tails is only half of the possibilities, as each could be inverse and it would still be true

>> No.12421302

<?php
// Copyright 2020 - Pajeet Sandeep
// 5+ year experience, graduate from University of New Delhi
// Written in PHP programming language

define("HEADS", 1);
define("TAILS", 0);

// This array to store valid tosses
$total_tosses_at_least_one_head = array();

// This array to store tosses double head
$total_both_heads = array();
for($i = 0; $i < 100000; $i++){
// Flip coins 1
$coin1 = mt_rand(0,1);

// Flipping coining 2
$coin2 = mt_rand(0,1);

// Test if coining 1 is head
if ($coin1 != TAILS && $coin1 == HEADS){

// This would be valid tossing so append to array
$total_tosses_at_least_one_head[] = mt_rand(0, mt_getrandmax());

// The first coining is heads, now lets test second coining!
if ($coin2 != TAILS && $coin2 == HEADS){
// The second coins is head!
// Append a random number to array
$total_both_heads[] = mt_rand(0, mt_getrandmax());
}
}

// Test if second coining is not tailing
if ($coin2 != TAILS && $coin2 == HEADS){

// This would be valid tossing so append to array
$total_tosses_at_least_one_head[] = mt_rand(0, mt_getrandmax());

// The second coining is heads, now lets test the first coining
if ($coin1 != TAILS && $coin1 == HEADS){
// The first coins is head as well!
// Append a random number to array
$total_both_heads[] = mt_rand(0, mt_getrandmax());
}
}

// If both of the coinings are HEAD then we need to remove 1 result!
if ($coin1 == HEADS && $coin2 == HEADS){
// Remove some elements from arrays!!
array_pop($total_both_heads);
array_pop($total_tosses_at_least_one_head);
}
}

// Count the elements in the arrayings and display on the computer screen
echo count($total_both_heads) / count($total_tosses_at_least_one_head);

// Result = 0.33518755669388
?>

>> No.12421709

>>12420953
>"At least one is heads" refers to "one" coin, among two.
"At least one is heads" refers to a number of coins among two that is not zero. {1, 2}

>> No.12421720

>>12420989
One coins being heads, OR two coins being heads.
X ≤ 2 ∪ X ≥ 1 = (X = 1) ∪ (X = 2)
X = {1, 2}
You have to consider both cases

>> No.12421734

>>12421009
>a number that isn't zero is not the same thing as at least one.
Considering we are dealing with natural numbers given positive discrete values, yes, it is the same.

>> No.12421742

>>12421302
based pajeet

>> No.12421758
File: 3 KB, 132x188, Untitled.png [View same] [iqdb] [saucenao] [google]
12421758

wouldn't it just be 50; same as one coin flip?

>> No.12421759
File: 22 KB, 1219x794, coins.png [View same] [iqdb] [saucenao] [google]
12421759

>>12421758
sorry, wrong photo

>> No.12421788

>>12421759
Yes. I see the problem now. With coin flips, there's an inherent ordering. When you're dealing with two doors opened in different ways, the order doesn't matter. This fact is occluded by memes, so anon ends up counting the two different configurations as the same.

>> No.12421807

>>12421758
TOSS THE FUCKING COINS IRL AND FIND OUT

>> No.12421810

>>12421758
HH happens 1/3 of all cases according to your picture

>> No.12421846

>>12421788
well, yeah. if one of two coins is guaranteed heads, then - obviously - only the other coin needs to be flipped, making it a 50% chance. i just included both guaranteed heads scenarios to make it more readable.
scenario 3 can be read in reverse order to be scenario 1 and scenario 4 can be read in reverse to be scenario 2. ultimately which coin is guaranteed heads is arbitrary

>> No.12421861
File: 34 KB, 1024x768, venn for brainlet anons.png [View same] [iqdb] [saucenao] [google]
12421861

>>12421759
Problem here is you consider the event HH (both heads) to actually be two separate events where each is part of either set when it's not.
HH is both part of (1st coin is heads) and (2nd coin is heads) in the sense that (1st coin is heads) ∩ (2nd coin is heads) = HH

>> No.12421867

>>12421861
i don't see the issue with that train of thought. whichever coin is guaranteed heads, there is one remaining coin to flip; which has a 50% chance of landing heads. HT, TH and HH are not 3 equally likely scenarios

>> No.12421880

>>12421846
if one of two coins is guaranteed heads, 1/3 of the time you will get both heads, not a 50% chance.
Because one of the two coins is guaranteed heads 3/4 of the time, and both are heads 1/4 of the time.
Given one of two coins is guaranteed heads, both are heads = 1/4 probability INSIDE that 3/4 probability: 1/4 / 3/4 = 1/3.
Sounds counter intuitive but was proven empirically idk how many times.

>> No.12421888

>>12421867
There is no coin guaranteed to ve heads

>> No.12421901

>>12421867
Look at your picture closely.
Your tree is not a representation of outcomes, in the sense that its two branches each represent one arbitrarily chosen event and the specific outcomes that satisfy its condition.
Scenario 2 and 4 are actually one and the same, you are just showing it is a child of each event, which is true, but the number of appearences in this tree doesn't represent the actual probability of outcomes. It's a hierarchy tree composed of selected sets and their child elements, some of which can belong to both at the same time, as shown in >>12421861
If the venn diagramm doesnt do it for you, >>12420422 is actually a very concise way of representing the different outcomes of the total set, each with aprobability of 1/4.

>> No.12421904

>>12421888
>You flip two coins, at least one is HEADS.
???

>>12421880
both of the coins being heads is only a 1/4 chance when no coins have guaranteed outcomes. (1/2*1/2) both coins being tails being eliminated brings up this chance as only one coin is chance dependent,

>> No.12421905

>>12421888
I think anon refers to "at least one is heads", in the sense that events that satisfy this condition are guaranteed to have one coin that is heads.
It doesn't refer to a specific coin of course, no actual order here.

>> No.12421914

>>12421904
>both of the coins being heads is only a 1/4 chance when no coins have guaranteed outcomes.
Of course, that is what "1/4 probability INSIDE that 3/4" means.
P( both are heads | at least one is heads ) = P ( both are heads ∩ at least one is heads ) / P( at least one is heads )
= P ( both are heads ) / P( at least one is heads ) = 1/4 / 3/4 = 1/3

>> No.12421926

>>12421901
wouldn't scenarios 2 and 4 being the same bring it back to being 50% chance? i feel like i'm being stubborn here but it just doesn't make sense to me how an outcome determined by one coin flip can be anything other than one half. whether the "second" or "first" coin is the guaranteed head the only factor separating a "both heads" and a "one heads" scenario is one coin flip.

>> No.12421935

https://youtu.be/Ke8TZj63F0Q

>> No.12421962

this thread has the highest proportion of bait ive ever seen. either that or mass hysteria.

>> No.12421965

>>12421926
>i feel like i'm being stubborn here
dont worry it's really not bad compared to what we've seen previously

Nothing tells us the coins are thrown consecutively, so there's no real order here.
However, since the coins are independant, we can use an order for labelling purposes.
The coins are independant.
That means the first coin being heads and the second being tails is NOT the same event as the first one being tails and the second being heads.
HT /= TH.

Looking at >>12420422, you can see the total set is composed of every possible event given 2 coins with 2 stats each : 2^2 = 4, with flat distribution, i.e. equal probability of 1/4.
Notice how the HT/TH comes up twice, that's why we make the distinction between the two events, in relation to the order we label them.
If we consider the condition "at least one is heads", we remove TT.
We are therefore dealing with 3 events. (which previously represented 3/4 of the total set)
Remember, each are distinct events with equal probability. The 3 of them share the total set with a probability of 1/3 each.
HH appears once with a probability of 1/3.

If I want to refer to the 1/4 / 3/4 thing, 4 is the total set, 3 is the events we keep that satisfy at least one is heads and 1 is the HH event. We remove TT and keep 3, only want HH so it's 1 out of 3.

>> No.12421987

>>12421962
all 3 threads make for over 1200+ posts combined lmao

>> No.12421989

>>12421926
Flip two coins. If it's TT, discard the trial, otherwise write down the result. Doesn't matter if you flip consecutively, or simultaneously, doesn't matter if the coins Are labeled or not. Do it until you have 100 trials written down.

"At least one is heads" is true for every pair in your list. But it's clear that the train of thought "1/2 chance first coin is heads, then 1/2 chance other coin is also heads etc." doesn't work here.

>> No.12422023 [DELETED] 
File: 72 KB, 220x220, 220.png [View same] [iqdb] [saucenao] [google]
12422023

>>12418876
>you flip 2 coins
>at least 1 is heads
You have the event of flipping two coins but then you added a constraint that makes no fucking sense. What if they're both tails? Competely nonsensical proplem. If anything it should say "if you look at one of the coins and it is heads, what is the probability that the other coin is heads" which is a trivial since both coins are presumably independent. The answer is 50%

>> No.12422027

>>12422023
t. doesn't know what conditional probability is

>> No.12422035

>>12422027
Fuck you

>> No.12422042

>>12421965
i get the logic here, but fail to see how both HH scenarios are counted as one but both non-HH scenarios aren't. as the probability of an HH scenario is the main question TH may as well = HT as they are both not HH

>> No.12422099

I flip two coins and one of them is heads. So I have
HH, HT, TH. HT is the same event as HT: one heads and one tails. So I have HH, and HT. So its 50/50 between the two: one heads one goals or two heads

>> No.12422113
File: 50 KB, 1218x832, coin diagram.png [View same] [iqdb] [saucenao] [google]
12422113

this is the conclusion i've come to; fairly sure it's airtight. just depends on how you interpret the question.

>> No.12422116

>>12422099
Hmmmm I am retarded. I was looking at it as if the question is H-, so what is the probability of second coin being heads or tails. If we did 1000 flips, we'd expect 250 HH, 250 HT, 250 TH, 250 TT. We know that TT is out of the question so we reduce our sample space to 250 HH, 250 HT, 250 TH. Know the question asks what is the probability that both are heads. It would 250/750, 1/3.

>> No.12422135

ITT: /sci/ seethes over what the probability of two 50/50 outcomes is.
Goddamn.

>> No.12422188

>>12422113
think about scenario 2 that you wrote down. How the fuck is TH going to occur in practice? If you have to guarantee atleast 1 heads then you have to throw any scenario with the first coin being tails out, because that elimates HH. That is not at all how you do "atleast 1 coin is heads" the only scenario that makes sense for the mathematical statement "atleast 1 heads" is scenario 1.

>> No.12422243

>>12422188
i just did that to demonstrate that the number coin that is guaranteed heads doesn't matter. take out that one and it still stands.

>> No.12422307

>>12422135
exactly, except you're wrong.

>> No.12422331

>>12422113
No you fucking mong, while your scenarios are true as seen here >>12419050, there's no two ways to interpret the question, rearanging the coins so that it's always the first one that's head is your own wrong headcanon

>> No.12422434

>>12420955
>Yeah, and?
And what? You're the one who asked me.

>> No.12422436

>>12420974
>Is referring to a coin flip in the pair being heads.
No, it's referring directly to the first clause of the sentence, not to something else.

>> No.12422441

>>12420979
>"At least one is heads"
Refers to two coin flips, which resulted in one or more heads.

>> No.12422445

>>12421004
>So you agree I'm right
I agree that the first clause of the sentence is two coin flips, not a single coin. You seem to disagree, but maybe you're not expressing yourself clearly.

>> No.12422447 [DELETED] 

>>12421037
>it should be of all coins where a head is observed, how many are part of a pair of heads.
>should be
I do realize you think question "should be" something different. Perhaps something exciting and bold, something which would allow you to favorably showcase your pet wikipedia article.

Alas, it's the same boring question it's always been, about two coin flips with a result of one or more heads.

>> No.12422450 [DELETED] 

>>12422445
>>12421037
>it should be of all coins where a head is observed, how many are part of a pair of heads.
>should be
I do realize you think the question "should be" something different. Perhaps something exciting and bold, something which would allow you to favorably showcase your pet wikipedia article.

Alas, it's the same boring question it's always been, about two coin flips with a result of one or more heads.

>> No.12422451

>>12421037
>it should be of all coins where a head is observed, how many are part of a pair of heads.
>should be
I do realize you think the question "should be" something different. Perhaps something exciting and bold, something which would allow you to favorably showcase your pet wikipedia article.

Alas, it's the same boring question it's always been, about two coin flips with a result of one or more heads.

>> No.12422457

It’s 50 %. Incorrectly scripted run-downs doesn’t prove anything. Shit in = shit out.

>> No.12422578

Why someone always have to post an uber shit tier bait thread like that and why the fuck everyone comes to answer and go on a crusade. Why the fuck won't you let these worthless fucking threads die?

>> No.12422618

>>12420164
Obsessed

>> No.12422643

>>12421023
>get two coins, toss both at the same time, record if there are 1 head or 2.
You already know one coin is heads, you just need to flip one coin.

>> No.12422645

>>12421709
>"At least one is heads" refers to a number of coins among two that is not zero. {1, 2}
This doesn't contradict anything I said. Only one coin is known to be heads.

>> No.12422648

>>12421720
I did consider both cases.

>>12421734
No, you said we are dealing with coordinates in R.

>> No.12422649

>>12421758
Yes.

>> No.12422651

>>12422643
>You already know one coin is heads,
No, all you know is that there are two coin flips, which resulted in one or more heads.
>you just need to flip one coin.
No, you already flipped two coins. You don't flip one of those two coins again later.

>> No.12422655

>>12422434
And how does that contradict anything I said?

>> No.12422660

>>12422655
How does what contradict what?

>> No.12422662

>>12422436
>No, it's referring directly to the first clause of the sentence, not to something else.
Yeah, I never said anything to the contrary. Obviously one coin in the pair being heads refers to the pair and not some other coins.

>> No.12422667

>>12422441
Right, it refers to a coin in the pair being heads.

>I agree that the first clause of the sentence is two coin flips, not a single coin.
OK, and what is your point?

>You seem to disagree
Where?

>> No.12422670

>>12422667
>>12422662
There is no reference to a single coin, only to the result of two coin flips.

>> No.12422671

>>12422451
>I do realize you think the question "should be" something different.
No, your method of representing the question should be different.

>> No.12422673

>>12422671
My method of representing the question is the question itself.

>> No.12422676

>>12422651
>No, all you know is that there are two coin flips, which resulted in one or more heads.
That doesn't disagree with anything I said.

>No, you already flipped two coins. You don't flip one of those two coins again later.
Flipping two coins and then looking at the result is not following the question. You don't get to look at the coins, you are only told one is heads. Therefore the only way of modeling the question is to stemming the probability the other coin is heads. This is done by flipping one coin.

>> No.12422678

>>12422660
How do your posts contradict my posts? I never said the second sentence is talking about other coins.

>> No.12422679

>>12422670
>There is no reference to a single coin
"At least one is heads"

>> No.12422680

>>12422673
Where in the question do you get to determine the results of both coins? You are only told one is heads.

>> No.12422683

>>12422679
>"At least one is heads"
This refers directly to the first clause of the sentence: "You flip two coins."

>> No.12422687

>>12422680
The result of both coins is one or more heads.

>> No.12422690

>>12422678
>I never said the second sentence is talking about other coins.
I never said you did.

>> No.12422691

>>12422683
>This refers directly to the first clause of the sentence: "You flip two coins."
Right, I never said it referred to some other coins. What is your point?

>> No.12422693

>>12422687
Where in the question do you get to determine the results of both coins? You are only told one is heads.

>>12422690
Then why are you repeatedly telling me it refers to the first sentence?

>> No.12422699

>you are only told one is heads
No, you are told that you flip two coins, which resulted in one or more heads. That all you're told. Nothing more, nothing less.

>> No.12422703

>>12422693
>Where in the question do you get to determine the results of both coins?
The part where it says "You flip two coins, at least one is heads."
>You are only told one is heads.
No, you are told that two coin flips results in one or more heads.

>> No.12422709

>>12422691
>What is your point?
That's what I'm asking you.

>> No.12422712

>>12422699
>which resulted in one or more heads.
Actually you're told "at least one is heads" which implies one or more heads. I don't know why you keep repeating non sequitur as responses.

>> No.12422716

>>12422703
>The part where it says "You flip two coins, at least one is heads."
That's only information about one coin. Saying it determines both coins is fake information.

>> No.12422717

>>12422693
>Then why are you repeatedly telling me it refers to the first sentence?
I'm not sure what your question is here? The second clause of the first sentence refers to the first clause of the first sentence.

>> No.12422719

>>12422709
No, you didn't ask that. You responded to my posts with non sequitur. Read my posts again if you don't get it.

>> No.12422724

>>12422717
>I'm not sure what your question is here?
Why are you repeatedly telling me the second clause of the first sentence refers to the first clause of the first sentence? I never said it doesn't.

>> No.12422726

>>12422712
>which implies one or more heads
Correct, one or more of two coin flips resulted in heads.
>>12422716
>That's only information about one coin
No, it's information about the result of two coin flips. The second clause refers directly to the first, not to something else.

>> No.12422734

>>12422724
>I never said it doesn't.
Yes, you keep saying the second clause of the sentence refers to a single coin, when it clearly refers to the first clause: "You flip two coins."

>> No.12422739

>>12422726
>No, it's information about the result of two coin flips.
One coin in the pair being heads is information about the two coin flips. I'm not going to respond to any more of these non sequiturs. Either give an argument or leave.

>> No.12422740

>>12422719
No, your posts say that the second clause of the sentence refers to a single coin, but the only referent is two coin flips.

>> No.12422741

>>12422734
The single coin is one of the two coins. You're not actually making an argument.

>> No.12422743

>>12422739
>One coin in the pair being heads is information about the two coin flips.
It would be, if we were given that information, but we weren't.

>> No.12422746

>>12422741
Which single coin? No single coin is ever referred to. The only reference is to the result of two coin flips.

>> No.12422766

>>12422743
We were given that information, it's just not information that determines the result of both coins, only one.

>> No.12422769

>>12422746
>Which single coin?
Whichever one is referred to as "one is heads." It didn't matter which one, since the probability is the same either way.

>> No.12422773

>>12422766
There is never a reference to any single coin, only to the result of two coin flips.

>> No.12422775

>>12422769
>Whichever one is referred to as "one is heads."
No single coin is ever referred to as being heads.

>> No.12422777

>>12422773
>There is never a reference to any single coin
"At least one is heads"

>> No.12422780

>>12422769
>Saying "one is heads" increases the chance of both coins being heads.

>> No.12422782

>>12422775
See >>12422777

>> No.12422789

>>12422777
>>12422782
That's a reference to the first clause of the sentence, "You flip two coins," not to anything else.

>> No.12422790

>>12422780
Saying one is heads increases the chance of one coin in the pair being heads to 1, yes. The other remains 1/2 since the coins are independent.

>> No.12422795

>>12422789
See >>12422739

>> No.12422807

>>12422795
See >>12422789

>> No.12422808

>>12422807
See >>12422795

>> No.12422810

>>12422808
See >>12422807

>> No.12422815

>>12422810
See >>12422808

>> No.12422816

>>12422790
>Saying one is heads
See >>12422789

>> No.12422820

>>12422815
See >>12422810

>> No.12422821
File: 234 KB, 1161x937, countif.jpg [View same] [iqdb] [saucenao] [google]
12422821

>>12418876
>>12418962
can someone smarter than me answer this question?
I did a simple excel demo. (yes I could have done it in less steps).
I sum up the iterations with at least one head and put them over the ones with two heads, and as you expect it is about 1/3, .3464 in red here.
What I don't get is why two heads over not two heads is also almost 1/3 (but not the same 1/3 using the same random numbers.) Shouldn't that be 1/4 because it is counting the tt? .360544 here bolded in red.
[its not very close to 1/3 because I only did 200 trials]

>> No.12422822

>>12422816
See >>12422780

>> No.12422825

>>12422822
See >>12422816

>> No.12422834

>>12422821
1/4 : 3/4 = 1 : 3

>> No.12422844

OP is right. It’s 1/2. HH is twice as likely as HT if at least one coin is heads!

>> No.12422852
File: 109 KB, 1353x592, AC3D1032-304C-49AF-A4BB-C800428B7256.jpg [View same] [iqdb] [saucenao] [google]
12422852

>>12422834
But then all you need to know is the probability of two heads to get the 1/3 answer for the op,
But that doesn’t make any sense. Knowing that at least one is heads should increase the odds that both are heads, but the odds are about the same, which suggest knowing one is heads is useless, which doesn’t make any sense

>> No.12422855

>>12422844
>if at least one coin is heads
No, if a single coin is heads. The question never refers to a single coin, only to the result of two coin flips.

>> No.12422884

>>12422855
I mean as likely. HH is as likely as HT and so the correct answer is 1/2. Any stupid moron can understand this.

>> No.12422893

>>12422852
That’s a big cock when you consider the size of the rest of the body.

>> No.12422903

>>12422852
You flip two coins.
(This is the sample space given by the first clause of the sentence.)
HH HT TH TT = 1/4 : 1/4 : 1/4 : 1/4
HH = 1/4 : 4/4 = 1/4

The result of those two coin flips contains at least one heads.
(This is the additional information given by the second clause of the sentence.)
HH HT TH = 1/4 : 1/4 : 1/4
HH = 1/4 : 3/4 = 1/3

The result of those two coin flips contains one distinct coin we know to be heads and one distinct coin we don't know.
(This information doesn't exist.)
HH HT = 1/4 : 1/4
HH = 1/4 : 2/4 = 1/2
or alternatively
Hh Ht hH tH = 1/4 : 1/4 : 1/4 : 1/4
HH = 2/4 : 2/4 = 1/2

>> No.12422918

>>12422903
you mean
>HH = 2/4 : 4/4 = 1/2

>> No.12422923

>>12422918
The last line, yes.

>> No.12422925

>>12422903
That doesn’t answer why 2 heads over not two heads =1/3 even when counting two tails.

>> No.12422932

>>12422884
Flip two coins.
Probability of two heads is 1/4
Probability of a heads and a tails is 1/2
Probability of two tails is 1/4.
The first two cases contain at least one heads.
>HH is as likely as HT
1/4=1/2.
>Any stupid moron can understand this.

>> No.12422936

>>12422925
Because you're dividing 1/4 by 3/4, rather than by 1.

>> No.12422938

"flip 2 coins" is meaningless if the result of one of the flips is pre-determined, so that phrase means "flip one coin", so the question reads: "flip one coin, what's the chance it will land on heads?"

hint: it's not 1/3

>> No.12422940

>>12419385
Nice code

>> No.12422943

>>12422938
>if the result of one of the flips is pre-determined
This information doesn't exist.

>> No.12422944

>>12422938
It is not pre-determined. Regard it as a game, in which two tails constitutes a reflip.

>> No.12422946

>>12422943
>at least one is heads

>> No.12422954

>>12422946
Refers to two coin flips, which resulted in one or more heads.

>> No.12422958
File: 783 KB, 1280x1589, F4EAA60F-5D45-4766-ACE0-E7967057E508.png [View same] [iqdb] [saucenao] [google]
12422958

>>12422936
Yes. Is it just a coincidence it’s the right answer? I am only using hh to get the 1/3 answer in the second forulma. I do not need to know one is heads and I still get 1/3. Becuase ai am counting tt as well

>> No.12422985

>>12422958
No, what you're doing is dividing HH by HT TH TT, instead of dividing HH by HH HT TH TT.

One of your calculations is correct: HH by HH TH HT to get 1/3.
The other leaves out HH in the sample space, which is why it's giving you an incorrect answer.

>> No.12423015

>>12422954
>>12422944
the complete roll space is heads-tails/heads-heads, which means we can omit the first heads and we just end up with tails/heads

>> No.12423020

>>12422903
>HH HT TH = 1/4 : 1/4 : 1/4
>HH = 1/4 : 3/4 = 1/3
This is the correct answer, not sure why you kept going
>HH HT = 1/4 : 1/4
Here, you’re not including TH as a possibility as well - if you wanted to combine HT and TH into one it would be
HH HT/TH = 1/4 : 1/2

>> No.12423023

>>12423015
No, the space is HH HT TH TT.

>> No.12423025

>>12423015
It doesn’t specify the 1st flip is the Heads flip, so tails-heads is just as likely as heads-tails (or heads-heads)

>> No.12423045

>>12423020
>not sure why you kept going
The third section:
>>12422903
>(This information doesn't exist.)
explains what extra information you'd need for the answer to be 1/2.

>> No.12423046

>>12423015
If you want to think about it like that, sure. But we have then [math] HH \mapsto \frac13 [/math] and [math] HT\mapsto \frac23 [/math] following from facts we already know about coin flips.

>> No.12423055

>>12423045
So your answer is 1/3?
Apologies I misunderstood what your comment was saying

>> No.12423063

>>12423055
Yes, I agree with you that the answer to OP is unambiguously 1/3.

>> No.12423080

>>12418876
I can never be fucked on all the variations, but this problem is part of a family that, if you're struggling with them, all have one secret to understanding the right answer.
>You need to select one thing to be your choices, and another to be your probabilities. Invert your problem setup, plug in the probabilities, and watch the orthodox answer appear.

>> No.12423308

THERE IS NO CONCRETE ANSWER
if you consider coin 1:heads+coin 2:tails and coin1:tails+coin 2:heads as scenarios that are necessarily different (i.e. coins being indexed)
then it's 1/3
if you consider them as effectively same scenarios, it's 1/2.
FUCK OFF WITH THESE MEME THREADS

>> No.12423336

>>12422042
>TH may as well = HT as they are both not HH
it's not just that they aren't HH.
Maybe instead of thinking about order think of it as flipping one coin in each hand (again, just for labeling purposes).
HT: Left hand coin is heads, right hand coin is tails
TH: Left hand coin is tails, right hand coin is heads
Two different events, each have a probability of 1/4.
HH: Both hands have coins. No two separate scenarios to this. Probability of 1/4.
Table on >>12420422 has all the information.
Also proven empirically on >>12419385 , look at the results down.
TT comes up 25% of the time, the combination of HT/TH comes up 50% of the time (1/4 + 1/4) and HH comes up 25% of the time.

>> No.12423340

>>12422116
very good on correcting yourself there anon

>> No.12423353

>>12422645
>This doesn't contradict anything I said.
It does. Because this shit:
>Only one coin is known to be heads.
You have {1, 2} and are only considering the {1}

>> No.12423356

>>12422648
>No, you said we are dealing with coordinates in R.
I never said such thing schizo
>OMG ITS YOU!!!! YOU'RE ANONYMOUS!!!!!

>I did consider both cases.
But you didn't:
>Only one coin is known to be heads.

>> No.12423365

>>12422740
this. he's so retarded

>> No.12423371

>>12422769
>>12422777
That statement can be made by seeing both coins and seeing they are both heads, which satisfies "at least one is heads"

>> No.12423386

>>12423308
>same scenarios
thing is they are not as shown empirically.
So first answer is the right answer

>> No.12423390

>>12423308
>THERE IS NO CONCRETE ANSWER
1/3 is the only answer that matches the information given in the question.
>if you consider them as effectively same scenarios
No information is given that would allow you to do that.

>> No.12423411

>>12423390
>No information is given that would allow you to do that.
and no information given doesn't allow it, that's why this meme is shit. it's up to interpretation as some people would consider 2/3 possible scenarios as effectively the same scenario.
should you not eliminate scenarios that are only different by technicalities that are not important?

>> No.12423429

>>12423411
>no information given doesn't allow it
You have to add information in order to allow it.

>> No.12423432

>>12423429
and you have to add information to index the coins

>> No.12423448

>>12423432
The first clause of the first sentence gives you that information. "You flip two coins" exactly and unambiguously gives you a sample space of HH HT TH TT.

>> No.12423457

"You flip two coins"
>consider the sample space {HH, TH, HT, TT} with uniform distribution P
"At least one is heads"
>define new distribution P'(A)= P(A|not TT)
"What's the probability that both are heads?"
>compute P'(HH)

it's not possible to pass an undergrad course in probability and see something different

>> No.12423464

>>12423411
no constraints => total sample space
constraints => total sample space - values removed by constraints
no information given about a certain characteristic of the set => no constraints on this characteristic

>> No.12423723

This is a textbook problem. The answer is 1/2

>> No.12424159

100%

>> No.12424406
File: 64 KB, 709x657, american coin.png [View same] [iqdb] [saucenao] [google]
12424406

>> No.12424434

>>12424406
Too much data to process without a denomination and date range. Perhaps RenTech could help.

>> No.12424616

>>12423723
explain the 1/2 answer i don’t get it

>> No.12424621
File: 378 KB, 2440x2164, coins.png [View same] [iqdb] [saucenao] [google]
12424621

>only assuming 1 dimension
did you guys drop out of elementary school?

>> No.12424646

>>12420422
>each square has an equal chance (25%) of occurring.
HH has double the chance
See >>12419486

>> No.12424661

>>12424646
1/2+1/2+1/4>1, dummy

>> No.12424677

This thread tells me everything I need to know about /sci/. Thanks. Saved me a lot of time.

>> No.12424688

>>12418876
You don't need to label the coins to get the right answer (1/3) because the 3 scenarios aren't all equally likely: #2 happens 1/2 of the time, and #1 and #3 happen 1/4 of the time. The probability of at least one coin being heads is #2+#3=1/2+1/4=3/4, and the probability of both is #3=1/4, so the answer is (1/4)/(3/4)=1/3.

>> No.12424689

>>12424677
This is the adult pool, have fun swimming in toddler piss.

>> No.12424692

>>12424646
>HH has double the chance
Of what?

>> No.12424727
File: 30 KB, 450x123, 58D83F5D-F2D0-4F22-A2EB-E84D1CFEBC53.jpg [View same] [iqdb] [saucenao] [google]
12424727

What did the R meister mean by this?
Did he literally dilate?

>> No.12424749

>>12424727
lazy caterer checked

>> No.12424776

There's no way there's this many low IQ mongrels ITT. Let me break down the possibilities.

If the left coin is the guaranteed heads:
HH
HT
If the right coin is the guaranteed heads
HH
TH
This brings the possibilities to:
HH
HH
HT
TH
Two of them are both heads out of the four combinations.
2/4 is 1/2.

>> No.12424781

>>12422643
That is not what "at least one coin is heads" means.

>> No.12424784

>>12424776
>If the left coin is the guaranteed heads:
>If the right coin is the guaranteed heads
not how it works, anon

>> No.12424829

>>12424784
>>12424781
Actual retard.

>> No.12424839

the confusion arrises from the fact that people what people perceive as "atleast one heads" is actually a STRICT SUBSET of "atleast one heads" and not an equality.

>I flip a coin and it is heads so atleast one is heads

yes that is a subset but not all of the scenarios that "atleast one heads" entails

>If the left coin is the guaranteed heads: If the right coin is the guaranteed heads

again a subset but not an equality.

>> No.12424841

>>12424829
see >>12419385

>> No.12424846

>>12424776
>Flip two coins:
>25% chance of both heads, 50% chance of one heads and one tails, 25% chance of both tails
>Flip two coins and announce whether a heads showed up
>Suddenly, 50% chance of both heads, 50% chance of a heads and a tails, 25% chance of both tails.
Amazing.

>> No.12425244

>>12422855
>No, if a single coin is heads.
A single coin is heads of at least one is heads, moron.

>> No.12425251

>>12423353
>>Only one coin is known to be heads.
>You have {1, 2} and are only considering the {1}
Not sure what you're talking about, you think the second coin is heads too?

>> No.12425254

>>12423356
>I never said such thing schizo
Then read the posts you're responding to retard.

>But you didn't:
>>Only one coin is known to be heads.
I did. Only one coin is known to be heads.

>> No.12425259

>>12422740
>No, your posts say that the second clause of the sentence refers to a single coin
It does. "At least one is heads."

>but the only referent is two coin flips.
The two flips contain the single heads.

>> No.12425264

>>12423371
>That statement can be made by seeing both coins
Who saw both coins? You're making up fake information not in the problem.

>> No.12425272

>>12423448
"at least one is heads" unambiguously tells you that the sample space is Hh hH Ht tH

>> No.12425276

>>12424692
HT or TH

>> No.12425279

>>12424781
It is. If you think anything else you are a schizo.

>> No.12425284

>>12424846
>>Flip two coins and announce whether a heads showed up
Actually it just says "at least one is heads"

>>Suddenly, 50% chance of both heads, 50% chance of a heads and a tails, 25% chance of both tails.
No, there's a 0% chance of both tails, you goddam retard. The chance of two heads is increased because two heads makes it twice as likely a heads is given.

>> No.12425289

>>12424839
There is no confusion, just a schizo who thinks his interpretation is the only one possible getting trolled by people who know it's an ambiguous problem.

>> No.12425317

>>12425251
>Not sure what you're talking about, you think the second coin is heads too?
I'm talking about this :
X being the number of known coins.
"At least one is heads" sets a lower limit. (X ≥ 1)
Two coins sets the upper limit. (X ≤ 2)
X ≤ 2 ∩ X ≥ 1 = (X = 1) ∪ (X = 2)
Two coins. "At least one is heads" can be concluded by seeing either one coin being heads, OR seeing both coins to find that both are heads or one is heads and the other is tails.
OR as in union. You need to consider all values in the resulting set.

>>12425254
>I did. Only one coin is known to be heads.
That is (X=1). You didn't consider (X=2). That is what I am trying to tell you.

>>12425264
>Who saw both coins? You're making up fake information not in the problem.
Not fake information. (X=2) is still in the resulting set. Inventing a constraint that removes it is fake information.

>> No.12425325

>>12418876
I gave a concise explanation of this problem in the last thread and no one listened to me so fuck off

>> No.12425351

>>12425325
what was your answer?

>> No.12425374

50%. The second flip has nothing to do with the result of the first flip

>> No.12425381

50% of anons don't know basic conditional probability

>> No.12425709

S

>> No.12425713

C

>> No.12425715

I

>> No.12425720

no no no

>> No.12425723

S

>> No.12425726

C

>> No.12425729

H

>> No.12425730

I

>> No.12425733

Z

>> No.12425735

O

>> No.12425737

T

>> No.12425739

H

>> No.12425744

R

>> No.12425745

E

>> No.12425746

A

>> No.12425750

D

>> No.12426099

[math]X[/math] - number of heads on both coins
[eqn]P(X = x) = \begin{cases} \frac{1}{4}, & x = 0 \\
\frac{1}{2}, & x = 1\\
\frac{1}{4}, & x = 2 \\
0 & \text{otherwise}
\end{cases}[/eqn]

at least one is heads - [math]P(X \geq 1) = P(X = 1) + P(X = 2) = \frac{3}{4}[/math]

both are heads - [math]P(X = 2) = \frac{1}{4}[/math]

both are heads with the constraint that at least one is heads - [math]P(X = 2 | X \geq 1) = \frac{P(X = 2)}{P(X \geq 1)} = \frac{\frac{1}{4}}{\frac{3}{4}} = \frac{1}{3}[/math]

>> No.12426139

The results is Theyre already both heads and tails

>> No.12426460

>>12425276
where does it say the coin is biased?

>> No.12426515

>>12425317
>X being the number of known coins.
>"At least one is heads" sets a lower limit. (X ≥ 1)
No, it doesn't say at least one is known, it says at least one is heads. If you can assume both are known why not just assume both are heads?

>You didn't consider (X=2).
I didn't add fake info to the problem.

>(X=2) is still in the resulting set.
Resulting set of what?

>> No.12426521

>>12426099
HH
HT
TH
TT

Half of the coins are heads so P(at least one is heads) = 1/2

P(both heads|at least one is heads) = (1/4)(1)/(1/2) = 1/2

>> No.12426525

>>12426460
Where did I say it was?

>> No.12426560

>>12425244
>A single coin is heads of at least one is heads
This would be true if there were at most one coin flip, but the first clause of the first sentence tells us there are two coin flips.

>> No.12426563

>>12426560
>This would be true if there were at most one coin flip
No, it's true either way. One coin is one coin regardless of other coins.

>> No.12426564

>>12425259
>It does. "At least one is heads."
No, that refers to the result of two coin flips, not to a single coin.
>The two flips contain the single heads.
There is no single heads. The two flips result in one or more heads, not in a single coin that is heads.

>> No.12426566

>>12425272
No, it reduces the sample space established by the first clause of the first sentence from HH HT TH TT to HH HT TH.
See >>12422903

>> No.12426568

>>12425289
>who know it's an ambiguous problem
Ambiguous means that something is open to more than one interpretation. OP is the opposite of that. Adding information that doesn't exist, information about a single coin, doesn't describe a different interpretation of the same question. It describes a different question.

>> No.12426575

>>12426563
>No, it's true either way.
No, if there are two or more flips that result in one or more heads, no information has been given about any single coin.

>> No.12426609

>>12426525
if HH is twice as likely as HT or TH that means P(H)=2/3, P(T)=1/3 why is the coin funny?

>> No.12426708

>>12426521
>Half of the coins are heads so P(at least one is heads) = 1/2
3 out of 4 cases satisfy "at least one is heads"