How smart is Sup Forums?

How smart is Sup Forums?

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math.stackexchange.com/questions/991060/flip-two-coins-if-at-least-one-is-heads-what-is-the-probability-of-both-being
en.wikipedia.org/wiki/Boy_or_Girl_paradox
twitter.com/SFWRedditVideos

>at least one
either 50% or 100%, depending on how many heads there were before.

What?

25%

1/3

Anyone who says 50% is either trolling or retarded.

75%

Wrong

SO what's the right answer? Can anyone explain? I'm shit at math.

>euro
Fuck off yuropoor

It has to be 50% right?

>American triggered by math

Here's all the outcomes for flipping 2 coins:

HT
TH
HH
TT

2x Tails isn't a valid option cause were looking for at least 1 heads, that leaves 3 options. 2x Heads is one possibility from 3 options, so 33%

50%

Two coins flipped.
It is given one is always heads. The other is either heads or tails. Therefore, it's 50/50

TH or HT doesn't matter because the order doesn't matter.

but isn't it somehow more likely that there's one head and one tails than two heads

There is no difference between HT and TH in this case.. they are the same since one of the coins is always heads

3 ways to get at least 1 heads

HH
HT
TH

HH is 1 of those 3

1/3

This one, there are 3 case with one head, and one of those is two heads, so its 1/3, basic math.

Yes.

66.666....% HT/TH
33.333....% HH

1/3

0%
coins never land on heads

1/3

Google gambler's fallacy

Thinking that the other coin has any Influence next is stupid.

If one is head the the other is simply 50/50

If we assume one is head then the question becomes "what are the odds of a coin flip showing head"

Sixth form S1 is where its at

1/3 anyone who says otherwise is retarded

50%. if we can assume that there will always be one head then all we have to figure out is the possibility of the seconding being a head.

second*

The probs for a single coin are 50%. Four combinations for two coins, three of them show any head at all. That's a total of 150% for the question.

Go to school an learn statistical maths. Stupid person.

Ok stupid fucks listen up.

Two coins are flipped and one will deffinitly land on heads cause plot. What is the chance both the coins land on heads?

The first coin is already stated to land on heads. And there are only two possible outcomes left, the second coin lands on heads or tails and thats a 50/50 chance.

So considering one coin is gonna land on heads guaranteed the question becomes: what is the chances that this single coin lands on heads.

The answer is %50

>one is head for sure
>the other one is 50/50
>50/50 that both land heads

One lands heads always, the other one either lands heads or not, so its 50/50, there are no other cases since the question is just the chance of both landing on heads

doubles of truth

At least one is heads, so that leaves 3 possibilities

TH, HT or HH.
HT and TH are NOT the same.
Getting just 1 heads is lower chance as getting both heads. But if we split up TH and HT they are equal chance as HH.

it doesn't say the first coin, it says at least one coin. It could be either coin. There fore there's three possible out comes.

HT
TH
HH

so 33%

But that isn't the question. Reread it.

It's simply if one coin shows head. What are the odds of the 2nd one showing also heads. Never mentions any specific order.

This. End of discussion.

51%

Everyone who thinks its 50% should go back to school lol

As right as your reason Ling may sound...

HE
HT
TH

There is no difference between TH and HT.

So what we have left is...

HH
HT/TH

50% mate.

The first coin is given, heads. What's the statistics of a second, indipendant flip being heads... 50%

>posting ambiguously worded math questions

One of the coins is definitely heads, so we disregard that coin. It does not affect the outcome of the other coin.

So basically 50%.

This is a basic conditional probability question and it does not contradict the Gambler's Fallacy.

Flip 2 regular coins. All possible outcomes are:

HH
HT
TH
TT

But we have a CONDITION; At least 1 coin landed heads.

There are 3 equally probable ways to get AT LEAST 1 heads coin from a 2 coin flip. These are

HH
HT
TH

Of those 3, ther is 1 case where both coins are heads

1/3

HT and TH are different.
If it didn't matter then just getting one heads is twice the chance of getting 2, but i don't see this addressed in your reasoning anywhere.

There is a difference between TH and HT, the question never says the first coin, it says at least one of them, could be either one.

It's fucking 50% you fuckin' mongols.

>There is no difference between TH and HT.

Yes there is. They are 2 separate and equally probable permutations. This is basic probability, user.

Think of it like this

Take two different coins. Let's say, a penny, and a quarter. Each coin has a 50% chance of landing either heads or tails. You flip both coins. What are the possible outcomes? Well, let's see:

penny = heads & quarter = heads
penny = heads & quarter = tails
penny = tails & quarter = heads
penny = tails & quarter = tails

4 possible outcomes. Each of them equally likely to occur (25% or 1/4)

Now, surely we can all see how the results,
penny = heads & quarter = tails
and
penny = tails & quarter = heads
are different, right? Surely you can see how these are two distinct, separate and equally probable outcomes, yes?

Answer is 1/3

627%

What's ambiguous about it?

HH and Ht are the same thing.
And no it doesnt specify which coin lands on heads, but that doesn't matter. The outcome of one coin doesn't affect the outcome of the other.

>One of the coins is definitely heads, so we disregard that coin.

Which coin?

Retard detected.

one coin lands heads, the other has a 50% chance of landing heads
HT/TH don't matter because the coins are identical and one WILL land heads without a specific order
i dont see whats so hard to understand, there are only 2 options

total 4 scenarios (2 x 2) - HH, HT, TH, TT. Knowing that one of them is heads we have HH, HT and TH left. Probability of HH is 33.(3)% or 1/3

Its 50%, anyone saying otherwise is wrong.

One if given, so you are only flipping one coin.

>The outcome of one coin doesn't affect the outcome of the other.

We know. The answer is still 1/3.

Pic Related

Wrong.

HT and TH are the same outcome.

50/50

And if you were to take that one of them is always heads, let's say, penny is heads, that leaves you with qrt able to go heads or tails, 50%, and that is it for that coin toss, if we were to assume the quarter is heads, that's a whole another coin toss

> implying statistics knowledge makes you smart

Odds of first coin being the heads coin: 1:2.

Odds of the second coin being the heads coin: 1:2.

Odds of the first coin being heads if second coin is the heads coin: 1:2.

Odds of second coin being heads if the first coin is the heads coin: 1:2.

Combine the odds: 1:2 x 1:2 x 1:2 x 1:2 = 1:16

Here we see how the knowledge of the given heads coin robs the chances of the other coin being heads.

50%

That's like saying this:

What are the odds of getting 2 heads when flipping 2 coins:

TH/HT
TT
HH

So it's 33%?

No it's not, it's 25% because HT and TH are not the same. If you treat them the same you should weigh their odds at 50% since when flipping 2 coins getting 1 heads is 50% chance.

It doesn't matter.

the coins are identical, it does not matter
one coin is out because it lands heads
the other 50%

>one coin lands heads
but which one

this is why HT vs TH matters, because you're not told which coin turns up heads

98.31647%

If you did it 100 times.
And you ignored all the results which didn't have at least one head.
Which fraction of the remainder would have both coins head?

fucking this, i dont think it could be explained easier for you retards

OP said at least one coin. Leading some people to believe that it is a specific coin that will always be heads and others to believe that it is unknown which coin is guaranteed heads. It makes all the difference.

Lol retard, there has to be one heads...

One has to land on heads. Which give you a 50% chance that the other will either land on head or the other will land on tails.

Keep in mind, the 1st coin is supposed to land on heads.

simple math kids.

>HT/TH don't matter because the coins are identical

They are 2 separate coins.

HT and TH are 2 separate and equally probable permutations.

For a 2 coin flip, these are the possible outcomes (probabilities in parentheses):

HH (25%)
HT (25%)
TH (25%)
TT (25%)

Or if you prefer it this way

HH (25%)
HT/TH (50%)
TT (25%)

As at least 1 lands heads TT is eliminated.

Pic Related: Bayes Theorem

Answer is 1/3

Well actually you do get 25% chance for HH or TT and 50% for HT/TH, which is the same..

It depends on the country. Irish 1 Euro coins don't have heads, thus 0% there.

Okay, this is true, but what if they were flipped chronologically? As in the one that landed heads was already flipped, and this is where the observer comes in. Now, this narrows it down to any option with H going first. HT and HH. TH and TT are impossible, not because the asker laid down a vague requirement, but because the "heads" hasn't been flipped like he said he has. Again this is all assuming that one was already flipped. I think that's where a lot of people got confused.

For anyone who thinks the answer is 50%, answer the question in the pic. Now you see how you are wrong.

Answer is 1/3

Roll

if its two same coins there is no way of telling and it does not matter, if one HAS to land heads the other has a 50% chance of doing the same

math.stackexchange.com/questions/991060/flip-two-coins-if-at-least-one-is-heads-what-is-the-probability-of-both-being
Faggots

>if it's two same coins there is no way of telling
so someone puts two identical quarters on a table in front of you and you immediately go "HOW DO I KEEP TRACK OF THESE SEPARATELY, IT'S IMPOSSIBLE"

But if we knew WHICH coin would be guaranteed heads it would be 50%

That's what I was trying to explain.

It doesn't matter. You have assumed the question demands constraints on the order of outcomes.

In practical application the answer is 1/2.

obviously, but you don't

Do your own homework nigger.

TT - no
HT - possible
HH - possible
50%

>HT/TH is not relevant

>Sup Forums
>stackexchange link
>o tempora, o mores

Oh it's this thread again. Needed to prove that your STEM degree was better than Gender Studies did you?

zzz this question is bait. It's years old for trolling on Sup Forums, its decades and decades old in general. The answer is 33%, trolls and idiots will say 50% and deny that when tossing the coins, TH and HT are two separate events.

en.wikipedia.org/wiki/Boy_or_Girl_paradox this question is a reformulation of this paradox.

why would that ever need proof

>what if they were flipped chronologically?

They can be flipped simultaneously, sequentially or you could simply flip a single coin twice.

In all cases where at least 1 coin (or flip) lands heads, you will get both heads (or 2 heads) 1/3 of the time.

The answer is 1/3 in all cases.

> As in the one that landed heads was already flipped, and this is where the observer comes in.

If 1 coin is flipped and it is observed to be heads, then of course the probability that the next flip is heads is 50%, but this is NOT the case in the OP question.

>I think that's where a lot of people got confused.

I think you might be correct, along with the fact that probability is often counter intuitive for most people.

Pic Related: Answer is 1/3

TH is also possible

1/3

>In practical application the answer is 1/2.

Don't ever gamble, you numbskull.

It depends on how you interpret the question you dumb fuck.

It can't be a fair toss though because one coin must always be heads, so therefore the answer is 50%.

so you're basicaly saying the coin that is not forced to land on heads has a higher chance of landing tails than heads?

No. Because it was not stated in the OP, order does not matter. TT Won't happen, and both TH HT are the same. It is a 50/50.

> From all families with two children, one child is selected at random, and the sex of that child is specified to be a boy. This would yield an answer of 1/2

^From your wikipedia article

From all possible outcomes of the coin flips, one coin is selected at random, and the side of that coin in specified to be heads. This would yield an answer of 1/2

Congrats, you proved yourself wrong

Do you know which coin? Because if not then there's three possible configurations for the coins to land.

TH
HT
HH

all three are distinct and satisfy the requirements of at least one head. All three have the same chance of occuring.

If we knew which coin would be heads then there would only be two options.

HT
HH

and then you'd be right.

But we don't know which one, and you're wrong.

What? No.

No coin is FORCED to land heads.

2 regular coins were flipped, and at least 1 of them landed heads by chance. it could be either coin. This means that EITHER coin could STILL be tails, just not BOTH.

This leaves 3 equally probable outcomes in the sample space

Heads - Heads
Heads - Tails
Tails - Heads

1/3

why doesnt someone just flip two coins a fuckton of times and comes back with an answer.

>and both TH HT are the same.

Don't be fucking stupid and read this Answer is 1/3

The result is the same, one coin is out of the equation, not knowing which one it is doesn't change a single thing.

>read every second word of the article
>instantly declare yourself smarter than every mathematician on earth
kill yourself.