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/sci/ - Science & Math

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4115800 No.4115800 [Reply] [Original]

Here's a proof that /sci/ is retarded.
You flip a fair coin twice. What is the probability that you will get heads twice?

>> No.4115802

1/3

>> No.4115803

>>4115800
0.5 because every flip is independent. Next?

>> No.4115804

1/2 * 1/2 = 1/4

>> No.4115806

>>4115803
please be trolling please be trolling

>> No.4115807

100%
next?

>> No.4115809

25%.

>>4115803

>0.5 because every flip is independent. Next?

Herp derpa derp. L2statistics.

>> No.4115814

1/4
anybody claiming anything else is either trolling or retarded.

>> No.4115811

>>4115802
this guy is right

you can have

HH
HT
TT

only 3 possibilities

so 1/3

>> No.4115816

>>4115811

Holy fuck, please, learn to do statistics, you're not in high school anymore.

It's 25%.

>> No.4115818

>>4115816
HH
HT
TT

3 outcomes

1 out of 3.

>> No.4115821

>>4115816
HT and TH are the same you fucking retard. It's 1/3

>> No.4115828

>>4115821
They are only the same if you don't consider order, in which case, it is twice as likely as HH or TT, so it's still 1/4. gtfo dipshit.

>> No.4115829

TOKIO HOTEL

>> No.4115833

>>4115828
how do you not understand this? OP is asking what are the chances of one particular outcome

there are 3 outcomes

QED the single chance of a particular outcome out of three is one out of three

>> No.4115834

>>4115821
>>4115818
>>4115811
>>4115803
>>4115802
OP delivers

>> No.4115835

>>4115818
>>4115821

It's how kids in 3rd year do probability, but it doesn't work here.

AND means MULTIPLICATION. What's the probability that the first coin is heads AND the second coin is heads.

1/2 * 1/2 = 1/4

Now shut up and go fresh up at Khan Academy.

>> No.4115836

>>4115800
1/2
If the coin is heads initially, it will become tails when you flip it. Then, when you flip it again, it will become heads again.
If the coin is tails initially, the converse will happen.
I assume that 'fair coin' means that the probability that the coin is heads initially is 1/2.

>> No.4115842

>>4115835
holy shit. coin flips are independent events. fucking dumb 12 year olds

>> No.4115844

>>4115828

just admit you're wrong and stupid, or leave, we will all forget about this thread in 10 min anyways.

>> No.4115845

>>4115836
-10/10

>> No.4115847

You 1/3 guys do realize that when you combine HT and TH that outcome has a higher chance of happening than the other two right? You guys aren't considering that

HH 25%
TH HT either one 50%
TT 25%

>> No.4115854

>>4115842

Fuck this, I'm not bothering anymore. Anyone saying 1/3 is just trolling or plain retarded.

>> No.4115855

>>4115847
lets pretend what you are saying its true.

3 outcomes

if one of them has twice the chance of happening.

then it would be

HH 33%
HT/TH 66%
TT 33%

>> No.4115861

>>4115845
>cannot into tossing a coin

>> No.4115863

>>4115855
lol covering your ass by going overboard and pretending you were trolling all along. Fuck off, retard.

>> No.4115864

TT, TH, HT, HH

25%

same as

1/2*1/1

1/4

>> No.4115865

>>4115861
nobody in here is tossing coins. learn to read.

>> No.4115867

http://onlinestatbook.com/chapter5/binomial.html to all the 1/3 retards

>> No.4115868

>>4115864
>1/2*1/1

1+1
2+1

1/3

>> No.4115871

>>4115802
>>4115811
>>4115818
>>4115821
>>4115842
>>4115844
Master troll.

>> No.4115872

>>4115868

Where does the 1/1 chance come from? The second coin has a 1/2 chance just as well.

>> No.4115876

>>4115871
>troll
>singular
Bravo for realizing the samefaggery.

>> No.4115878

>>4115867
You made an entire fucking website just to troll?

>> No.4115879

>>4115878
Of course I did

>> No.4115880

>>4115855

yep 3 outcomes 1 has twice the chance of the other two 25 50 25 works and so does yours but yours is incorrect because you're not considering the original statistics from if you had 4 outcomes which is 25 25 25 25 so when you combine the 2 you get 50 instead of 66

>> No.4115881

>>4115865
Exactly. That's why the process is fully deterministic, given the starting state.

>> No.4115883

It's 1/4.
<div class="math">
P(A) \times P(B) = P(A~and~B)
</div>
<div class="math">
\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}
</div>

>> No.4115886

>>4115880
33% x 2 = 66%

>> No.4115887

>implying HT is the same as TH

there are four possible outcomes leaving you with a 1/4 chance of rolling HH

>> No.4115888
File: 170 KB, 400x525, 1323132307295.jpg [View same] [iqdb] [saucenao] [google]
4115888

>>4115855
This one was actually funny.

>> No.4115889

>>4115886
LOL SO OGIRINAL I TROOOOOOOOOL YOU XDDDDDDD

>> No.4115898

lol at people still posting correct answers as if it matters in the least

>> No.4115902

>>4115886

25% * 2 = 50%

>> No.4115905

>>4115902
Really? You felt the need to clarify that?

>> No.4115907

>>4115855

>133%

Fox News would love to have you work for them!

>> No.4115910

H1 - 50% -> H2 has 50% again, T2 has 50% again
T1 - 50% -- H2 has 50% again, T2 has 50% again
We want H1 + H2. The first one has 50% to occur. The second one has 50% again. That means that the probability for both to occur at the same time is P1+P2 (first heads' 50% + and second heads' 50%) which is 1/4 or 25%

>> No.4115913

>>4115910
50% + 50% = 100%

facepalm.jpg

how do you fail such simple addition.

>> No.4115916

>>4115905

Well as this guy pointed out >>4115907

They seem to have terrible math skills so yes I did feel the need to tell them 25 times 2 is 50 if they insist they're probability is correct when they're getting a total over 100%

>> No.4115923 [DELETED] 
File: 75 KB, 686x1214, trollexploitable2.png [View same] [iqdb] [saucenao] [google]
4115923

>>4115800

>> No.4115931

>>4115916
Two possibilities: 1) they are faggot trolls, in which case, they likely know their fallacies, 2) they are completely fucking retarded, in which case they will not believe your posts. Meh.

>> No.4115951

0.5
divided by two

>> No.4115959

>2011
>responding to some of the most blatant trolls of all time
>ISHYGDDT

>> No.4115969

1/18

you have three possibilities:
HH
HT
TT

BUT you're flipping the coin twice, so it's 1/3*1/3, which is 1/9. but like everyone said, since you're flipping it twice you also have to divide by two. so it's 1/22

>> No.4115997

>>4115969
You forgot adding the Herm factor, that is multiplying a number by 2 and then dividing it by 2, giving you 9000+ gigawatts

>> No.4115993

If you flip an unfair coin that lands on heads 25% of the time and tails 75% of the time, what is the probability that it lands on heads?

It's obviously 50% because there are two possibilities, heads or tails.

>> No.4116030

everybody here is trolling and stupid at the same time

>> No.4116038

>>4116030
yeah, especially all the people who said it's 25%. lol, dumbasses

>> No.4116049

lol coin probability is quantized in non classical situations so don't forget the factor of h-bar.

you can only solve this to within a probability-wave distribution.

>> No.4116054

T
HT
HH

1/3

>> No.4116060

>>4116054
you forgot TT and TH, so it should be 1/5

>> No.4116063 [DELETED] 
File: 364 KB, 444x722, posh_constanza.png [View same] [iqdb] [saucenao] [google]
4116063

>>4116060
>2011
>trolling badly and/or sucking balls at probability
ISHYGDDT

>> No.4116067

but what if the quarter lands on its edge?

>> No.4116069 [DELETED] 

>>4116067
A coin that is actually flipped cant possibly ever land on its edge.

>> No.4116073

>>4116069
wouldnt that depend on the surface that the quarter is landing on?

>> No.4116078 [DELETED] 

>>4116073
oh right, i was meaning for a hard surface like a table, if you flip it onto jelly or something it might stick in and land on its edge or something....

>> No.4116079

1/5

HH
HT
TH
TT
Tyrone steals the coins before they land.

>> No.4116080

>>4116069
on the surface of someones hand? no

>> No.4116077
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4116077

>replying to "do my homework" threads thinly veiled as "lol, you're to stupid to figure this out" threads with the correct answer
>2011

>> No.4116082 [DELETED] 
File: 7 KB, 527x395, afriendlyreminder.png [View same] [iqdb] [saucenao] [google]
4116082

>>4116069

>> No.4116088

>>4116079
the odds of tyrone stealing the coin would vary depending on the distance between the coin flipper and the ghetto, so if you let D represent the distance between the coin flipper and the nearest ghetto in meters, then the answer would be

1/4 * sqrt(D/1000) + sqrt(1- D/1000) If D < 1000
1/4 if D >= 1000

>> No.4116089 [DELETED] 

>>4116069
Take your pills.

Then retake physics.

>> No.4116090
File: 166 KB, 317x699, op-his-thread-his-life.jpg [View same] [iqdb] [saucenao] [google]
4116090

Hi OP, how does it feel to have just wasted 1 hour of your life samefagging a shitty troll thread?

>> No.4116092
File: 34 KB, 431x450, I got this.jpg [View same] [iqdb] [saucenao] [google]
4116092

If your space is
HH
HT
TH
TT
then
P(HH)=1/4

it's a binomial outcome so the number of possibilities is 2^(number of trials).
i.e:
1 coin = 2^1 = 2 outcomes
2 coins = 2^2 = 4 outcomes
3 coins = 2^3 = 8 outcomes.
4 coins = 2^4..etc.

>> No.4116098

>>4116092
>>4116092

OP did not specify whether ordered mattered or not.

>> No.4116101

>>4116098
That is true, I forgot to mention assuming order doesn't matter.

>> No.4116109

>>4116101
it doesn't matter, HH = HH. the odds of getting one tail and one heads are 50% whether you track order or not

>> No.4116110

Only 3 options BUT -HT has a higher probability of being selected as it can happen more than one way >
Not all outcomes of HH, HT, TT are equally likely...
but i prefer to think of it in terms of the sample space

>> No.4116128

1/2 probability of heads on a single flip.

1/2 probability the first time
1/2 probability the second time

1/2 * 1/2 probability both times = 1/4

If you think otherwise, then 0/10

>> No.4116149

How the fuck did /sci/ got in such a dilema with a so simple thing.

anyway, i think there are more options. what if the coin just stays standed? it can happen. then how would it be the probabilities?

>> No.4116163

Why are people still responding to this trollfest?

>> No.4116235

OP obviously means there is a fair coin lying flat. You then flip it over twice. Not a toss just flip it over. Coin goes from heads to tails or from tails to heads. Either way after it is flipped over again there will be a zero percent chance that it be heads after both flips.

Nice try 1/4 tards.

>> No.4116265

HT
TH
HH---->this one
TT

1/4 of possible outcomes
25% chance

OP wins due to anon's stupidity

>> No.4116273

can either land heads, tails, or on the rim.

1/3*1/3= 1/9

shppoooopity poopity pooooooo!

>> No.4116282

the first coin can be heads, and the second tails

the first coin can be tails, and the second heads.

TH and HT are NOT the same

>> No.4116304

>>4115800
There is no probability.

Throwing a coin isn't something random, it's air density, movement and your muscles moving and preforming work. If you knew how strong to throw/fling it you could make whatever result you want.

>> No.4116305

>>4116235
> 1/4 tards
I lol'd but I like "twenty-five-percentards" better.

>> No.4116310

Agreed.

"twenty-five-percentards"

>> No.4116312

I conducted an independent trial in which 4 separate people each tossed 2 coins twice and the data indicates a 0% chance of a coin being heads followed by another coin being heads.

>> No.4116320

>>4116312
So much for the "greater-than-zero-percentards" conspiracy theories.

>> No.4116331

1/2
you either do or you don't

>> No.4116339

>>4116331
0/10

you didn't troll me, asshole

>> No.4116361

<span class="math">P(A) \times P(B) = P(A\bigcap B)[/spoiler]

Seriously guys HOW RETARDED ARE YOU REALLY

25 %

>> No.4116545

0
no such thing as a fair coin

>> No.4116551

you can't say that because humans tend to throw in a likewise way every time. The chance of it repeating the same result is thus by just a little factor higher.

>> No.4116596

P(H, H) = P(0.5*0.5) = 0.25 (or 1/4). Basic probability, I don't know how people still have these questions.

>> No.4116610

potential Outcomes:

Heads and heads
Tails and tails
heads and tails
tails and heads


heads/tails combo is the same as tails/heads in terms of what side you have facing up. So that's 1 single outcome. Op doesn't specify a difference between coins to consider them 2 separate outcomes

heads/heads then is 1 of 3 outcomes.

>> No.4116690

>>4116610
2/10

>> No.4116765

>>4115811

sorry but there are 4 possibilities in the sample space: {HH, TT TH HT}. So the chance of getting HH is 1/4 in this classical probability problem. Another way of putting this is, the probability of getting HH on two fair coin flips is 2C2/(2C1 * 2C1), which is the number of ways to choose 2 particular faces (heads or tails) from 2 particular faces (which is obviously 1) divided by the number of ways to choose 1 face from 2 possible faces, which is on the first coin flip, also times the number of ways to choose 1 face from 2 possible faces on the second coin flip... So we have 1/(2*2) = 1/4.

If anyone says I'm wrong, fuck you, I'm a math major.

>> No.4116824

>"92 posts and 7 image replies omitted"

Good job op, you actually proved that /sci/ is a retarded place.

>> No.4118555 [DELETED] 
File: 9 KB, 308x264, faggot.jpg [View same] [iqdb] [saucenao] [google]
4118555

>>4116824

>> No.4118561

>>4118555
please not again with this bumping of threads that are over 6 hours old.

>> No.4118592

here you go fucking tards

http://www.wolframalpha.com/input/?i=2+coin+tosses

>> No.4118615

This is just a bastardization of the boy-or-girl paradox.
http://en.wikipedia.org/wiki/Boy_or_Girl_paradox

The way the question is phrased allows it to be interpreted in two different ways. People are giving different answers because the questions they are answering are logically not the same. There is no conclusive right way to interpret the question. A paradox isn't a question that's hard to answer, its a question with multiple equally valid but conflicting answers.

>> No.4118619

1/4

can't believe this thread is still here.

>> No.4118630

>>4118615
No. No, it isn't. Not even close. There is zero ambiguity here. The answer is 1/4.

>> No.4118632

FUCK.

HH
HT
TH
TT

1/4 CASE CLOSED SHERLOCK HOLMES JESUS IT'S LIKE YOU GUYS FELL OUT OF THE FUCKING UGLY DOUCHEBAG MONGOLOID TREE AND LICKED EVERY BRANCH ON THE WAY DOWN THEN CLIMBED IT TO DO IT ALL AGAIN AD INFINITUM.

PROTIP: IN THIS INSTANCE HT AND TH ARE NOT THE SAME, THEY ARE AN ENTIRELY SEPARATE OUTCOME YOU FUCKING RETARDS.

100/10 DAMN RIGHT I MAD

>> No.4118639

>>4118630
Seriously, you are going to post the methodology to the answer for the 6+th time?

>> No.4118670

it's probability and not statistics btw

>> No.4118686

Question is not defined enough, Does the order matter?
If so 1/4
Does the order not matter?
If so 1/3.

>> No.4118690

>>4115811
You forgot HT

>> No.4118692

>>4118686
Doesn't matter if the order matters or not you window licking tard. All that means is that HT/TH then has a greater chance to happen than HH or TT, meaning it's still 1/4 chance of getting HH.

>> No.4118694

>>4115800

.....H - TH
T<
.....T - TT

.....H - HH
H<
.....T - HT

1 in 4 chance from tree diagram

1/2 * 1/2 = 1/4

1/4 chance from multiplication

>> No.4118703

Anyone posting correct answers are either stupider or more trolltastic than those who were posting incorrect answers earlier.

>> No.4118711

K flipped it 20 times here are my results
TT-TH-HH-HH-HT-HH-TT-TH-HT-HH-TH-HT-HH-HT-HH-TH-HH-TT-TT-TH
HH: 7/20
thats about 35%
sorry onefourthtards

>> No.4118734

>>4118711
I flipped it a million times and got 0.250751.

>> No.4118751

>>4118711
>>4118734
I flipped it 0 times and got that you guys are faggots.

>> No.4118772

This thread obviously proved /sci/ is retarded, because it fulfilled the premise of the question: it answered a troll.