# coin flip

• Bronze
Joined: 04.12.2007
A question. Does anybody know how to calculate the probability of exactly four coins falling on the same side, if you through 10 coins?
• 15 replies
• Bronze
Joined: 23.07.2007
• Bronze
Joined: 04.12.2007
Thanks. I-m studying for a statistics exam
• Bronze
Joined: 21.09.2007
why study? just learn about statistics by playing poker
• Bronze
Joined: 23.07.2007
Well you're not the only one writting on this forum who's statistics exam real soon
• Bronze
Joined: 04.12.2007
Lol. Yeah learning by playing poker... one time I tried to learn for an english test by watching TV It didn't work I'll just stick to the classic method. When's your exam?
• Bronze
Joined: 23.07.2007
Next friday. The bad thing is we already did binomial distribution years ago, now there are some weird tests: Kruskall-Wallis, Anova, chi-square ad so on...
• Bronze
Joined: 04.12.2007
Wow. My exam is this Friday. What do you study, math? We didn't do any of those things, but than again we have a very shorten version, since it's more of a side coarse. Well lots of luck and knowledge on your exam
• Bronze
Joined: 23.07.2007
It's not that complicated, it just looks as if it was.
I study chemistry and biotechnology so it's also not really leading subject here. What do you study? And in which country?

By the way, I agree with the fact that watching tv don't provide you any knowledge at all . Only medical dramas do
• Bronze
Joined: 04.12.2007
Well I don't completely agree. I did learn most of my English from watching TV when I was a kid I study law, statistics is meant as a subject that broadens your horizons, sort of speak. Biotechnology... that's interesting, like frenkenstien and stuff - just kidding. Never liked chemistry too much dough, had a really bitchy teacher in high school

Oh yeah, I'm from Slovenia

And concerning my original question. I still don't know how to calculate it. I know how to calculate combinations with a binominal simbol, but that's only if you have like 4 different things and you're trying to put them in a group of 2, and then how to calculate how many different combinations of the group there are. But here I'm trying to calculate how many combinations there are where 4 coins out of 10 fall on the side whit the number(X).

If I knew that it would be a simple equation:

A:Four out of ten coins fall on the side with the number on it.

P(A)= this is the one I don't know.)/10!

Because the number of all possible combinations, when you through 10 couns is 10!. But I don't know how many combinations there are where only 4 coins fall on the correct side.

Please feel free to correct me if I'm wrong
• Bronze
Joined: 23.07.2007
Law - that's the kind of studies that will provide you some decent work, not the chemistry... But what's poker for I'll work for fun and play for life

Hello from Poland! I've spoken once to a Slovenian, we nearly managed to understand each other while talking our native languages. Funny .

And according your question: you're right about the number of combination. Now the number of 4 coins falling on one side and 4 on another. Assume that "x" is one side and "o" the other:

xxxxoooooo
xxxoxooooo
xxxooxoooo
xxxoooxooo
...
xxoxxooooo
xxoxoxoooo
xxoxooxooo

Pretty lot of counting, isn't it? I suggest you try the other way.

If you want to calculate the probability of 4 coins landing on one side and 6 on another, you calculate ( 10 over 4 ) * 0,5^4 * 0,5^6 - the first symbol's called Newton's symbol (in Polish at least) and it's calculated like that: (10 over 4) = 10! / ((10-4)! * 4!). First 0,5 is the probability of success, 4 is the fraction of success and so on. Here we have the same probability of success and loss, so the ending value is (10! * 0,5^10) / (6! * 4!) =~ 0,205078125, so about 20,5%. This is fine if you now what side of coin is a success. If you want to say what's the probability of coin falling on one of the sides 4 times and on another 6 times, it's 41%.

Uff. Hope my poor english didn't wreck the whole explaination.

• Bronze
Joined: 03.10.2007
if you're allowed calculators it's just 10C4/(2^10) = 0.2051

i think
• Bronze
Joined: 04.12.2007
Gee thanks. Yeah, you are both correct. And don't worry your english didn't ruin the explanation, I just have to decode it, since I don't know a lot of the technical terms

Well law is for life, and poker is for fun, I guess. But I would rather play than study for half of my life. But till that happens I'll stick to studying

And of course you understood each other, these are all languages of the same origin. I spoked to some Chezks a while back, you know what the funny thing was, they understood me, but I only understood a word here and there Guess some understand more than others.

Anyway thanks for all the help.

By the way 098799, where do you play, and whats with the nickname, it's pretty original? Any special meaning?
• Bronze
Joined: 23.07.2007
Good luck at your exam then!

And about me - I play at party exclusively, when I started at everest and stars it was just one big downswing. About the nickname - at party I'm johnykalesony, it has some pretty funny meaning in Polish. And 098799 - it has also some, let's say sentimental, meaning. But I'm not revealing it .
• Bronze
Joined: 04.12.2007
lol. I think I know what johnykalesony is. Not sure dough. Ok, I respect that you don't want to reveal it, I was just wondering since it's not very common that people construct there nicks only from numbers.

Well good luck to you too(on your exam as well as at the tables) and thanks for all the help.

Oh, and congratulation for making it to gold

Bye
• Bronze
Joined: 23.07.2007
Thanks, good luck for you as well.

I used to be gold before, just don't really play regular sessions. And I used to be a loosing player. Hope the past form of the verb is adequate in this sitiuation .

You can read about my ups and downs in user news section of this forum if you really have nothing to do . Writting a journal is somehow a good way to stop making stupid mistakes (not all of them though) - if you have the perspective of writting about your tilt, you just don't tilt .

See you at the tables.