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General => The Lobby => Topic started by: russell on January 31, 2009, 07:21:29 PM

Title: random math question
Post by: russell on January 31, 2009, 07:21:29 PM
if I do something five times and there's a 10% chance of succeeding each time, what is the chance that I will have succeeded at least once after all five times?


Title: Re: random math question
Post by: Geno on January 31, 2009, 07:22:55 PM
where's felt
Title: Re: random math question
Post by: Mettalik on January 31, 2009, 07:39:32 PM
Quote from: Geno on January 31, 2009, 07:22:55 PM
where's felt
superbananaplace: i don't know

AHHHHHHHHHHH  >.<
Title: Re: random math question
Post by: Wrench on January 31, 2009, 07:41:45 PM
10%
Title: Re: random math question
Post by: Tri4se on January 31, 2009, 07:47:48 PM
10%

I think
Title: Re: random math question
Post by: russell on January 31, 2009, 07:54:15 PM
Quote from: Tri4se on January 31, 2009, 07:47:48 PM
10%

I think


I thought that made sense, but then I thought it might not.  doodthing;
Title: Re: random math question
Post by: Tri4se on January 31, 2009, 07:57:14 PM
Quote from: 'Ð½Ð¾',кел on January 31, 2009, 07:54:15 PM
I thought that made sense, but then I thought it might not.  doodthing;
Well at first I thought it was .001%, but that's getting all 5 right. You're just asking for one. So 10%
Title: Re: random math question
Post by: guff on January 31, 2009, 07:59:53 PM
combinatorics THE POWER OF GOD

since order doesn't count, we'll use the binomial coefficient and because you're looking for at least one success we'll sum up the probabilities of each of one through five successes bassir;
if i remember all this correctly, then i think we would be dealing with 5c1 / 10 + 5c2 / 10^2 + 5c3 / 10^3 + 5c4 / 10^4 + 5c5 / 10^5 which gives you a probability of .61051 so that's about a 61% chance  akudood;
Title: Re: random math question
Post by: russell on January 31, 2009, 08:09:08 PM
Quote from: guff on January 31, 2009, 07:59:53 PM
combinatronics THE POWER OF GOD

since order doesn't count, we'll use the binomial coefficient and because you're looking for at least one success we'll sum up the probabilities of each of one through five successes bassir;
if i remember all this correctly, then i think we would be dealing with 5c1 / 10 + 5c2 / 10^2 + 5c3 / 10^3 + 5c4 / 10^4 + 5c5 / 10^5 which gives you a probability of .61051 so that's about a 61% chance  akudood;


That's good

Title: Re: random math question
Post by: guff on January 31, 2009, 08:12:29 PM
Quote from: 'Ð½Ð¾',кел on January 31, 2009, 08:09:08 PM
That's good


actually i think i might have screwed up somewhere because after running a few quick tests in python it seems to be closer to 41% but hey i'm a hell of a lot closer than everyone else so far and combinatorics really isn't my thing  akudood;
Title: Re: random math question
Post by: Tri4se on January 31, 2009, 08:13:33 PM
Quote from: guff on January 31, 2009, 08:12:29 PM
actually i think i might have screwed up somewhere because after running a few quick tests in python it seems to be closer to 41% but hey i'm a hell of a lot closer than everyone else so far and combinatorics really isn't my thing  akudood;
Teach me to speak math.
Title: Re: random math question
Post by: Travis on January 31, 2009, 08:14:57 PM
Quote from: guff on January 31, 2009, 08:12:29 PM
actually i think i might have screwed up somewhere because after running a few quick tests in python it seems to be closer to 41% but hey i'm a hell of a lot closer than everyone else so far and combinatorics really isn't my thing  akudood;
teach me to do math
Title: Re: random math question
Post by: guff on January 31, 2009, 08:17:43 PM
oh durr i overthunked it n_u

the probability of no successes is [tex](1 - .1)^5 = .59049[/tex], and since we're looking for the probability of one or more successes, that's the same as [tex]1 - P(no successes) = .40951[/tex] which fits with the 41% i was getting in my testing okay problem solved  akudood;
Quote from: Nothing on January 31, 2009, 08:14:57 PM
teach me to do math
okay today's class is on commutative operations in ordered fields i hope you've read chapter 4
Quote from: Tri4se on January 31, 2009, 08:13:33 PM
Teach me to speak math.
okay done  n_u
Title: Re: random math question
Post by: l a c e y on January 31, 2009, 10:20:06 PM
67
Title: Re: random math question
Post by: Pancake Paraphernalia on January 31, 2009, 10:39:51 PM
at first i was liek wat then guff made good sense because all losing is .9^5 so that's how there's .59049 and so it could b one win or moar but if all lose, that's like opposite, so if probablilites of these 2 opposites you get 1 so then 1-.59049 and so there you get .40951. I see it now.  hocuspocus;
Title: Re: random math question
Post by: Daddy on January 31, 2009, 10:46:04 PM
100 because you won't fail
Title: Re: random math question
Post by: Tri4se on January 31, 2009, 10:48:43 PM
Quote from: Dumb kewn;_; on January 31, 2009, 10:46:04 PM
100 because you won't fail
that's the spirit
Title: Re: random math question
Post by: Walter on February 01, 2009, 07:58:00 AM
Well, whats the chance of you failing all of them? Minus that from 100%  baddood;

Edit: In case you are a moron, 100 * (1 - .9^5)