How smart is /b/?

50%

Same odds as flipping one coin

1/3

1/4

>>724059238
eurofag

50.5%

1̲
3

File: Virion_(FE13_Artwork).png (2MB, 1876x1712px) Image search: [Google]

2MB, 1876x1712px

((1/2)x (1/2)x2)+(1/2)x(1/2)
=3/4

>>724059324
incredibly retarded pls kys

Two number 9s

>>724059238
1 to 3 chance.

1. Heads followed by another Heads, i.e. our winner
2. Heads followed by Tails
3. Tails followed by Heads.

Tails followed by another Tails can be ignored due to the premise that at least one coin landed Heads, so if the first coin is Tails the second one is by default Heads, lest it fails the premise of the excercise.
This is all obviously assuming that order of coin toss matters.

>>724059238
are you asking what the odds are for one heads or two, because you're making the question unclear to trigger a /b/tarded argument (again)

>>724059305
>>724059324
>>724059378
>>724059470

We got some stupid people here.

>>724059238
This shit again? It depends upon interpretation.

But hey I'm sure it'll get 500 replies so good on you OP you faggot.

File: coinsprobfags.png (16KB, 590x491px) Image search: [Google]

16KB, 590x491px

>>724059885
>because you're making the question unclear

The question is clear.

>What is the probability that both coins landed heads given at least 1 coin landed heads?

Protip: Answer is 1/3

25% chance.

One coin, two sides, 50%
Two coins, 4 sides total, 25% chance that both coins fall on heads at the same time

>>724060024
>depends upon interpretation.
>what is 2+2?
>DEPENDS ON INTERPRETATION

No, you're just a fucking retard.

1/3.

>>724059238
If one landed on heads then it is out of the question so 50%. we just learned stuff like this in school

>>724060082

That's before the condition that at least 1 coin landed heads and includes tails-tails as an outcome. tails-tails cannot be the outcome given the condition.

1/3

>>724060221
>we just learned stuff like this in school

Get off 4chan you underaged faggot.

>If one landed on heads then it is out of the question
O rly? Which coin is out of the question? Which 1 landed heads?

>>724059885
The instruction is pretty clear. OP doesn't nee to make unclear instructions because most /b/tards are really bad at math but confident enough to post their guess anyway, see
>>724059305
>>724059324
>>724059378
>>724059470
>>724059697
This thread will hit bump limit.

And yeah, the answer is 1/3, see>>724059844

>>724060156
you could say the first coin doesn't matter because it's fixed so it's 50% chance

>>724060865
>you could say the first coin doesn't matter because it's fixed

How is it fixed if it could be tails and the second coin heads?

Please think before showing how retarded you are.

>>724059844
what if it lands on its side

File: 1426865428083.jpg (5KB, 124x121px) Image search: [Google]

5KB, 124x121px

>>724061201
Yes and this is how these threads read bump limits.

Because faggots like you refuse to see it from a different perspective.

Kill yourselves all of you

2
1 + 1 = 2

>>724061411
>Can't figure out a math problem
>"Waaaah kill yourselves waaaah"
>"He won't see it from my perspective"
Inb4 underage ban

The answer is either 1/3 or 1/2, depending on how you know "at least one of them landed heads." Hence the ambiguity in the question, hence the endless arguments.

https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

File: 0.gif (1MB, 400x242px) Image search: [Google]

1MB, 400x242px

what do you mean regular coins? usually 1 side is more likely to be facing upwards than the other.
It has something to do with weight on the coin and spread of mass.

Should we assume that these coins are perfectly weighted and that the odds are exactly 50/50 when flipping a single coin?

And is it possible that the coin can land on the middle and remain standing?
It's very unlikely, but it does happen to some coins

>>724061411

You mean I refuse to see it from the incorrect perspective.

You're retarded. Congratz.

50% chance of heads x 2 = 100% chance both are heads

File: poor-child.jpg (96KB, 724x720px) Image search: [Google]

96KB, 724x720px

>>724059238
>ITT: everybody pretends conditional probability is optional.

HH
HT
TH
TT

TTis impossible in our world, so we are left with

HT - 1/3 chance
TH - 1/3 chance
HH - 1/3 chance

answer is 1/3

>but anon, HT and TH are the same outcome!

no they aren't, you assclown, but if you want to combine those events you have to combine their probabilities as well

HT/TH - 2/3 chance
HH - 1/3 chance

answer remains 1/3

>but anon, the problem says you set one coin on heads, its given in the problem!

ok kiddo, rewrite the wikipedia page and see how long that argument sticks.
https://en.wikipedia.org/wiki/Conditional_probability

>>724059238
Its a poorly worded question the "given that" bs is there to throw you off.
The answer is 25%, the probability of each coin landing on either head or tails is 0.5, 0.5 x 0.5 = 0.25. Simple

File: underestimate_power.gif (2MB, 565x236px) Image search: [Google]

2MB, 565x236px

>>724061811
from my point of view You are retarded

File: shitlord1.png (265KB, 501x408px) Image search: [Google]

265KB, 501x408px

>>724062357
Yes it's 1/3 but dont cite Wikipedia as fact.

their moderators are selling corrections left right center.

>>724062758

That's because you're legitimately retarded. I pointed out the logical flaw in your perspective and you double down like a dumbfuck instead of admitting your error.

Well done.

File: coins3.jpg (18KB, 470x342px) Image search: [Google]

18KB, 470x342px

>>724062669

>never heard of conditional probability
>gets a basic conditional probability question wrong

What a surprise.

The answer is 1/3, morons.

>>724062357
Possiblities: HH HT TH TT
Probability: 25% 25% 25% 25%
Possibility that is relevant to this question: HH
The answer is 25%

>>724063460
TT cannot happen as per OP's rules.

>>724063460
>TT
>at least one coin will land heads
>failing to reduce the solution space when an event is found to be impossible

For fucks sake. One already landed heads. There is no need to find the probability for that one, only the one that has not landed yet. So the answer is .50 or 50% because you are looking for the probability that coin #2 will become heads after #1 already landed as heads.

>>724063814
show in the problem where a coin has already landed.

>>724063460
>ignores the condition

This is why you fail at math.

Answer is 1/3.

50%

>>724063946
"Given that at least one of them already landed heads" So,that means that coin A or coin B already landed heads, so all we need to do is find the probability of whichever coin that has not landed. That means we are finding the probability of one coin landing heads because the other coin will always land heads based on what OP stated.

File: 39966-rosencrantz_amp_guildenstern_dead.jpg (32KB, 480x357px) Image search: [Google]

32KB, 480x357px

100%

60%

>>724059347
>>724059378
>>724059470
>>724059671
>>724059697
>>724059844
>>724060024
>>724060066
>>724060082
>>724060156
>>724060235
>>724060323
>>724060336
>>724061201
>>724061702
>>724061741
>>724061811
>>724062357
>>724062669
>>724063078
>>724063119
>>724063295
>>724063460
>>724064349
>>724063946
>>724064821

>being this retarded
50% faggots

Best I can do is 19%.

File: coinsprob (2).jpg (15KB, 461x366px) Image search: [Google]

15KB, 461x366px

>>724064507
>"Given that at least one of them already landed heads" So,that means that coin A or coin B already landed heads

Correct. That gives us 3 equally likely outcomes containing at least 1 heads coin.

coinA - coinB
Heads - Heads
Heads - Tails
Tails - Heads

Heads-Heads is 1 of those 3 equally likely outcomes.

1 of 3

1/3

use Bayes' theorem for math solution.

>>724060066
You moron, it doesnt matter which coin is heads or tails

This would be more accurat
HH -> 50% chance
TH
TT -> not possible

File: 23266068.jpg (113KB, 400x400px) Image search: [Google]

113KB, 400x400px

>>724065535

Ansir is nigger in 57

>>72406329
fucking nerd

>>724065535
>it doesnt matter which coin is heads or tails

Yes, it does, because:
The first coin could be heads
or
the second coin could be heads
or
both coins could be heads

3 equally probable outcomes containing at least 1 heads.

1/3

Stay in school, kid.

>>724059238
trick question
landing heads is statistically impossible because tails never fails

>>724065998
>It doesn't because it's the gambler's fallacy nigger.

File: 1486570498882.jpg (101KB, 423x750px) Image search: [Google]

101KB, 423x750px

>>724066012
Top kek

>>724063946
It's specified that one coin landed heads, but it's not specified how we know that... and that piece of information is what makes the difference. Hence the ambiguity in the question.

"The paradox occurs when it is not known how the statement "at least one is [heads]" was generated. Either answer [1/3 or 1/2] could be correct, based on what is assumed"
https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

>Scenario A

100 people flip pairs of coins. They get to see the results.

You dismiss everyone who flipped tails/tails.

If you pick one person's coin pair from this population, the probability of heads/heads is 1/3. This is the "restricted sample space" approach that most people here are describing.

>Scenario B

100 people flip pairs of coins. They get to see the results.

From all of the coins, you pick one at random, and it's heads.

The probability of that person's other coin being heads is 1/2, because it's independent of the first coin.

The probability increases in scenario B because you have more information.

see also http://economics-files.pomona.edu/GarySmith/Two-Child%20Paradox.pdf

>>724059238
25 percent

around 45% since one is guarantied to be heads and the head side is heavier so it is slightly more likely to be tails. So it is around 45-49% chance.

File: 2016-09-02 23_10_56-Mail.png (22KB, 879x504px) Image search: [Google]

22KB, 879x504px

>>724059238
Oh look, it's this thread again.

File: coinss.jpg (119KB, 1600x900px) Image search: [Google]

119KB, 1600x900px

>>724066137

Conditional Probability does not contradict the Gambler's Fallacy.

the answer is 1/3.

Do you need me to draw you more diagrams?

>>724066494
Dumbass.
GIVEN ONE IS HEADS, thats means first one will always be heads. So no tails then heads. 50%

>>724066494
>yes your right
>your wrong

Holy fuck this is some strange form of newfag I've never seen before

>>724066444
trip confirms

>>724066682
Which one of those two is heads?

>>724066137
https://en.wikipedia.org/wiki/Gambler's_fallacy

That's not the gamblers fallacy, moron.

The answer is 1 out of 3.

>>724066682
>thats means first one will always be heads

No it doesn't. Are you actually retarded?

At least one does not mean the FIRST one.

>having to explain the English language

Truly, /b/ is the most retarded board.

1/3

>>724066784

What?

50/50

HT

HH

>>724067022
Regardless of which one is heads, the odds can only apply to one coin since one is definitely heads

File: 1486928268237.png (1MB, 1280x720px) Image search: [Google]

1MB, 1280x720px

>>724059238
50%

It's a single instance of one coin flip because one's already on heads, getting tails tails isn't a factor, and it's impossible.

If you wanna be a complete ass you can try to argue there's 3 possiblities, heads heads, heads tails, tails heads, but you'd be wrong.

>>724059238
0.5

I think there are two ways to look at this problem and it depends how the word "given" is interpreted.

1. The mathematically correct way. 4 possibilities are HH HT TH TT. Since TT is not an option we are only left with HH, HT, and TH. So that makes it 1:3.

2. Interpreting the word "given" so that it means one will always land heads. You are given the circumstance where one is heads, period. What are the odds the other coin will be heads? 1:2 obviously.

I think the correct answer is 1:3 but I understand how people can interpret the question as the 2nd option.

>>724067180
>Regardless of which one is heads, the odds can only apply to one coin since one is definitely heads

incorrect.

EITHER coin could be tails, just not both at the same time. This gives 3 possible outcomes

heads heads
heads tails
tails heads

1/3

>>724067100
or TH

1/3

>>724067223

Seems logical, but it doesn't work that way. Try it - go grab a coin, flip it 20 times, and work out the % of two head flips vs getting at least one heads.

>>724067336
Sorry I mean grab two coins, flip them at the same time, and work out:

(two heads flipped) / (at least one heads flipped)

>>724067319
TH is the same as HT because in both scenarios the H was already decided

Run a real world experiment. Take two coins, sit one heads up and flip the other 100 times. See how many times you get heads

File: coinsvisualexplanation.jpg (740KB, 2442x1998px) Image search: [Google]

740KB, 2442x1998px

>>724067223
>getting tails tails isn't a factor, and it's impossible.

Correct. So you agree that in a normal case without a condition, there are 4 possible outcomes to a 2-coin flip. These are

HH 25%
HT 25%
TH 25%
TT 25%

So if TT is the only outcome not possible, you are left with 3 equally probable outcomes which all satisfy the condition of having at least 1 heads.

1/3

>>724059238
If one coin is going to land on heads no matter what, then you can take that out of the equation. Therefore, the odds are 50/50. The second coin could land on either heads or tails. That is two options. 100% divided by two possible outcomes results in a chance of 50/50. This is bait, bit its good bait. Heads and tails = 50%. Heads and heads = 50%. Tails and tails is not possible. The answer is a 50/50 chance that both will land on heads. Please, stop being retarded.

>>724067336
20 is a small sample size. I'm willing to bet that even 1,000 flips would vary from the true probabilities by 1 or 2 %. Real life isn't so predictable.

>>724067319
It doesn't fucking matter which one is heads, HT, TH are both the same outcome. One on heads, and one on tails. If the question was "what would the next coin land on, then your conditional bullshit would matter

File: TwuUAjsF-coins_chuckcross_eyeem_gettyimagesjpg-1210-680.jpg (176KB, 1210x680px) Image search: [Google]

176KB, 1210x680px

> Regular coins
>Posts European coins

Reported

>>724065998
Let's assume there's no first or second coin. They both get flipped at the same time. Does your answer still make sense to you?

>>724067556
But HT and TH are the same outcome

>>724067533
>TH is the same as HT
No, it isn't.

There are two independent coin tosses. They both must be considered in the stats

>>724067319
TH or HT are the same thing the fact is that it's a 50% chance given one will always be heads. Btfo

>>724067315
problem with the 2nd argument is you have to first take the first sentence as true and both coins were indeed flipped. So you have to account for the 3 possible outcomes even if its a given that one of the two will land heads.

>>724059238
I'll bite your dick off and shit in your fucking ear

File: coinsss.jpg (53KB, 360x640px) Image search: [Google]

53KB, 360x640px

>>724067533
>TH is the same as HT

You're retarded. So after you read this explanation, NEVER speak to me again.

HT is NOT the same as TH.

Imagine using a penny and quarter. If either the penny or the quarter landed heads, you could have:

penny=heads, quarter = heads
or
penny=heads, quarter = tails
or
penny=tails, quarter = heads

3 equally likely outcomes containing at least 1 heads

1/3

Still a chance it lands on its edge. A very small chance but still a chance

>>724067784
A toss implies there's a chance it won't be heads. One is already set as heads

Again, try it in the real world

Set coin 1 as H, flip another 100 times

Set coin 2 as H, flip another 100 times

>>724067747
>But HT and TH are the same outcome

No they're not, you dumbass. Just because they LOOK the same doesn't mean they aren't two separate and distinct events.

holy shit I knew /b/ was dumb but not THIS fucking dumb. I hope you're trolling.

>>724067906
>I can't actually argue, better throw out some insults

All these autists arguing that theyre right and the other is wrong. This question is age old bait, it's deliberately vague so that both 1/3 and 1/2 can be right and neither is wrong, you idiots are arguing over nothing, like always.

>>724068001

You're fixing a specific coin.

OP question does NOT fix any specific coin.

Either coin could be tails, just not both simultaneously.

HH
HT
TH

1/3

>>724068025
As far as the odds are concerned, they're the same.

Set coin 1 as H, flip another 100 times

Set coin 2 as H, flip another 100 times

>>724067645
See:
>>724066444

>>724068108

>gave explanation
>gave math solution
>gave diagram

Yeah, so you got me. you're trolling. I get it.

1/3

>>724068230
Then get 2 coins and try it for real, retard.

Conditional probability, motherfucker.

>>724068109

Answer to OP is actually 1/3.

It's basic conditional probability.

>>724068230
>As far as the odds are concerned, they're the same.

No they're not.

>>724068174
>OP question does NOT fix any specific coin.

Arguably it does. That's the ambiguous part, because it's not specified how we know that at least one coin landed heads.

>>724060336
dumbass.

>OP flipped two coins
>one was heads.
>what are the probability that the other was heads

in other words

>OP flipped two coins
>what are the odds both are heads

25% you faggot

>>724068174
No, I'm fixing both coins. That's all possible outcomes as far as the definite heads is concerned

That's why it's 1/2

75%

>>724067784
I see now why this is such a good trolling question. People have different assumptions on whether TH and HT are the same, ie. if you can distinguish between coins. I'd say you can't, because they are both coins. But if you believe TH is a different outcome than HT then 1/3 is correct.

Anyway I believe the question doesn't say whether they are flipped at the same or sequentially on purpose. And it doesn't mention if they are indistinguishable or not.

>>724068398

>2 coins were flipped
>At least one landed heads

That's not fixing a coin, retard.

>>724068371
Yes, they are

Set coin 1 as H, flip another 100 times

Set coin 2 as H, flip another 100 times

I'm betting the 1/3 fags think sticking on the door you picked in the Monty Hall paradox is 50/50

>>724068477

In a manner of speaking, it is. See here:

>>724066339

>>724068109
Yep, correct answer.

>>724067586
Holy fucking shit I just realized this is absolutely wrong. The people that are saying 1/3 are totally right. It never says that the first one is heads. It just says that EITHER one is heads. Therefore, I'm a dumbass, and the possible outcomes are:
>First coin (heads) second coin (tails)
>First coin (tails) second coin (heads)
>first coin (heads) second coin (heads)
I feel really stupid. The answer actually is 1/3.

>>724067747
I like to just break it down into two seperate instances because you could argue about it, but if th was the same as ht then it'd be 1/3 I guess, but what are the odds the coin never lands and enters orbit?

File: CoinsSimulation.png (111KB, 641x650px) Image search: [Google]

111KB, 641x650px

A = "both coins are heads"
B = "at least one coin is heads"

P(A|B) = P(A∩B)/(P(B)) = (1/4)/(3/4) = 1/3

This is a conditional probability question, so use Bayes' theorem to solve.
P(A|B) = P(A∩B)/(P(B))

Explanation for faggots:

COnditional probability questions take the form:
>What is the probability of Event A given Event B?

OPs question is
>What is the probability that BOTH coins landed heads, given that AT LEAST ONE coin landed heads?

So here

A = "both coins are heads" = {(HH)} = 1/4
B = "at least one coin is heads" = {(HH), (HT), (TH)} = 3/4

P(A|B) = P(A∩B)/(P(B)) = (1/4)/(3/4) = 1/3

Pic Related: Simulation confirms 1/3

The coins have already been flipped, you 1/3tards.

The situation is that I'm not going to flip coins, but rather, I've already flipped two coins, and let's say one is in each hand. I open one of my hands, and reveal that it's heads. What's the probability that the other coin is also heads? 50%.

Can't believe retards are falling for the 1/3 bait so easily.

>>724068621

No, because we understand probability.

We know you should switch.

We also know the answer to OP question is 1/3, because we're not mathematically illiterate.

File: coins.jpg (39KB, 370x277px) Image search: [Google]

39KB, 370x277px

If you think the answer is 50%, answer Pic Related.

File: Cant count to potato.jpg (32KB, 477x367px) Image search: [Google]

32KB, 477x367px

Nobody has considered the very real possibility that a nigger is in the room. In which case the chances of either coin hitting the floor before being stolen has to be factored in surely

>>724068826
>I open one of my hands, and reveal that it's heads

NOT the same as OP question, dumbass. You are adding information that ISN'T included in teh OP question.

The answer to your scenario is 1/2.

the answer to OP question is 1/3.

>if we know the first will be heads, what are the chances of second being heads
1/2
>if we know at least one of the coins will be heads what is the chance of both being heads
1/3

It's all in how the question is worded, it's 1/3 by the way.

the answer is 100% you fucking retards
if you flip two coins and we know one of them is heads,
then we only have one coin to predict. but the question clearly says one of them is heads, so we know the coin HAS to be heads.
it's a trick question, looks like you fucking imbeciles never finished 1/3rd grade

File: 1487129783585s.jpg (3KB, 107x125px) Image search: [Google]

3KB, 107x125px

All possible answers are
00
01
10
11
Since one of them has to be heads remove 00
there for there is a 33.333% chance both land on heads.

>>724059238

50%. There's a 50% chance both coins land on the same face, and a 50% chance they land on opposite faces. If you pick a coin, it will be either heads or tails, but the other will be different or the same with a 50% chance anyways. Picking a coin and knowing it landed on something doesn't change that.

>>724069184
No, I'm just helping you retards understand OP's question. Apparently no one here understands tense in the English language.

>>724059238
50%

>>724069330
No, because 01 and 10 are basically the same thing in this scenario. So it's 10 or 11. 50%

File: Uni_Wash_Cond_Prob.jpg (137KB, 921x631px) Image search: [Google]

137KB, 921x631px

>>724069421

Are you genuinely thick?

The whole point is that you DON'T KNOW which coin is the heads coin.

It could be EITHER coin or both.

heads, heads
or
heads, tails
or
tails, heads

1/3

Your scenario is 1/2 because you are given the information on WHICH coin is heads.

Pic Related: Answer to OP is 1/3

Source: Washington University (See slide 4)
http://courses.cs.washington.edu/courses/cse312/11wi/slides/04cprob.pdf

Lets use some awesome math here:
We know either of them must land on heads, but don't know which one it will be, presenting 2 scenarios (I use factors, 50% = 0.5 etc)
Unsure and heads OR heads and unsure
Unsure and heads is 0.5x1
Heads and unsure is 1x0.5
0.5x1+1x0.5 =
0.5+0.5 =
1
so a 100% chance :D

File: coins_events.png (10KB, 501x348px) Image search: [Google]

10KB, 501x348px

>>724069646
>because 01 and 10 are basically the same thing in this scenario

If you're not trolling, you should probably kill yourself, or at the very least never have children.

1/3

>>724069095
All possible outcomes considering each coin.
TT
TT
HT
TH
HH
HH

All the proof you need assuming no niggers.

>>724069646
Watch a Khan Academy video on probability buddy.

>>724059238
2 coins, meaning there are 2x2 possible variations:
TT
HT
TH
HH

Given that we know that one is heads, we can exclude the possibility that includes no coins having flipped heads, leaving:

TH
HT
HH

Since there are 3 possibilities in which at least one coin was flipped heads, and only one of them includes both flipping heads, the probability is one in three, or 1/3.

/thread

it depends on whether or not the coin belonged to a jew or not if it did we'll never find out