I have an event that has a 75% chance of happening. If I run the trial seven times, what is the probability of the event happening at least once? And what's the math behind it?
posted by jackypaper on Nov 6, 2009 - 7 answers

What's a fair way to chose winners for this ad-hoc giveaway? details inside... [more inside]
posted by smelvis on Oct 26, 2009 - 4 answers

How do I get a controlled distribution of random numbers to fairly determine a start position. [more inside]
posted by monkeystronghold on Oct 25, 2009 - 21 answers

Some guy recently got 3 holes in one on the same course (different holes) within 5 days. My cousin contends that the odds against this are 5 billion to one, based on something he read. He's willing to have me prove him wrong, but this is well beyond my ability to calculate. I'm good with any time period -- the likelihood of someone doing this in a year, or 10 years, or whatever. [more inside]
posted by jeather on Sep 21, 2009 - 24 answers

What is the probability of one or both events occurring. [more inside]
posted by charlesminus on Sep 18, 2009 - 5 answers

How do you multiply probability across multiple chances? Let's say that every time you roll a die, you have a one-in-six chance of having five come up. What math would you perform to come up with the probability of five coming up at some point with the dice being rolled two times? Three? Five? Ten? (I'm using dice as a shorthand here: the actual probability figure I'm working with is 24%.)
posted by WCityMike on Sep 16, 2009 - 15 answers

I have a bucket containing N marbles: M white marbles and N-M black marbles. I need to grab a handful of marbles (n) and figure out the probability of having picked up m white marbles. [more inside]
posted by Blazecock Pileon on Nov 6, 2008 - 16 answers

What are the chances, in blackjack, that I will start with 15, and the dealer will be showing a 10 (or face card worth 10)? [more inside]
posted by gummo on Oct 28, 2008 - 8 answers

It's late, I'm tired, and I have a probability and coding question that's fairly simple. [more inside]
posted by chrisamiller on Aug 13, 2008 - 10 answers

You're dealt 8 cards face down from a 52 card deck. All values are determined by the number on the card, not the suit. What is the probability of each card being dealt? [more inside]
posted by b_thinky on Jul 9, 2008 - 12 answers

Imagine a contest, with 21 judges and 4 contestants. Judges must give one contestant 4 points, one contestant 3 points, one contestant 2 points, and one contestant 1 point. The winner is decided by summing the scores of all 21 judges. Mathematically speaking, what percentage of the time would you expect there to be a tie for first place after all 21 scores have been added?
posted by 23skidoo on Jun 24, 2008 - 25 answers

How would the many-worlds interpretation work on the human level, if at all? [more inside]
posted by Rhaomi on May 24, 2008 - 38 answers

How many times would I have to roll a standard 6-sided die to get a statistically representative view of whether it was truly random or not? [more inside]
posted by Bugbread on Apr 30, 2008 - 8 answers

Suppose you take a test for a rare type of cancer that affects 0.01 percent of the population. The test is 98 percent reliable. You get a positive reading. What are the chances you have the cancer? I read this probability puzzle today and the writer said the statistical chances of you having the cancer in this scenario are less than half a percent. I don't get it. Isn't the rarity factor irrelevant compared with the test reliability? Please explain.
posted by binturong on Apr 12, 2008 - 24 answers

Mathematics filter: What are the odds of a pair of my friends meeting another couple who are also my friends, but they have never met before? Bonus. This happened on vacation in another city where neither of them, nor I, have ever lived... Is this an example of six degrees of separation?
posted by Gungho on Apr 1, 2008 - 16 answers

for the statisticians: what probability distribution do I want to fit to my data, and how? [more inside]
posted by russm on Jan 18, 2008 - 17 answers

I need a tool to help me analyze the probability of certain events occurring regarding a pool of X dice for a game I am creating. See my examples below. [more inside]
posted by DetonatedManiac on Dec 21, 2007 - 7 answers

Given a fair die with s sides, what is the expected number of rolls r before I get o outcomes with the same value v in a row? [Note this is emphatically NOT a homework problem; I just really want to know, feel like I should be able to figure it out, can't, and it is driving me nuts.] [more inside]
posted by lucasks on Dec 19, 2007 - 30 answers

Probability/stat question: I'm looking for patterns in a protein sequence, and I've found a few that occur quite frequently. How do I know these are actual patterns and not just an artifact of random amino acid distribution? [more inside]
posted by reformedjerk on Jun 19, 2007 - 11 answers

English grammar: 'could be Xing' versus 'can be Xing' -- how can we explain why one is correct and one isn't? [more inside]
posted by stavrosthewonderchicken on Dec 12, 2006 - 23 answers

ProbabilityFilter: Calling all mathematicians... [more inside]
posted by 777 on Nov 21, 2006 - 26 answers

A regular deck of 52 cards is shuffled and turned face up one by one. What are the odds of going through the whole deck and finding at least one set of two consecutive cards which have the same value? (ie, a pair). [more inside]
posted by jaimev on Nov 17, 2006 - 27 answers

MathFilter: Okay, I've got this gumball machine, which contains an infinite amount of gumballs, evenly distributed between 100 different flavors... [more inside]
posted by rifflesby on Sep 1, 2006 - 10 answers

Which city is safer: San Francisco or Philadelphia? [more inside]
posted by rorycberger on Aug 10, 2006 - 14 answers

4 different models of a toy are sold in identical, sealed boxes. Assuming the 4 different models are produced/sold/distributed in equal numbers, etc..., what are the chances of buying only 4 boxes, chosen at random (at different times, even), and getting all 4 different toys? [more inside]
posted by ab3 on Jun 2, 2006 - 12 answers

Probability filter: How do you determine the odds of being extremely unlucky? [more inside]
posted by TonyRobots on May 26, 2006 - 7 answers

Probability of one binomially-distributed variable being greater than another one - is there a closed form for this? [more inside]
posted by wanderingmind on May 25, 2006 - 11 answers

Math questions about permutations for those so inclined... [more inside]
posted by TheFeatheredMullet on May 5, 2006 - 28 answers

There are 10 possible exam topics. 6 will appear on the paper. 2 questions must be attempted. How well is an ass covered based on the number of topics covered? [more inside]
posted by kenaman on Apr 25, 2006 - 13 answers

Baseball Score Probabilities: Is it any more likely that the combined score of a Major League Baseball game will be even than odd (or vice versa)? [more inside]
posted by The Bellman on Apr 19, 2006 - 16 answers

If there's a 20 percent chance of rain on Monday, a 20 percent chance on Tuesday, and a 30 percent chance on Wednesday, what's the overall chance that it'll rain during this three-day period? How do you calculate this?
posted by futility closet on Apr 13, 2006 - 60 answers

So lets say I've got probabilities for 64 teams... [more inside]
posted by JPD on Mar 13, 2006 - 13 answers

Looking for ideas for teaching probability to kids. [more inside]
posted by carterk on Feb 6, 2006 - 16 answers

Probability: A coworker is having an issue with deriving a few formulas for a Weibull distribution. Any pointers? [more inside]
posted by TommyH on Nov 7, 2005 - 2 answers

If a company is holding a series of 24 raffles where they give away a prize, and you have 24 raffle tickets which can be used in any number of raffles you choose, do you have better odds entering one ticket per draw, or using them all in one draw? This is assuming that the number of other participants in the raffle is roughly the same from draw-to-draw.
posted by Jairus on Oct 3, 2005 - 17 answers

In my exploration of poker odds and strategies, I've developed more programs for examining situations. I need help evaluating some of the probability and statistics involved. [more inside]
posted by RustyBrooks on Jun 5, 2005 - 10 answers

Probability question (more...) [more inside]
posted by trharlan on Jan 24, 2005 - 16 answers

Suppose there are 20 objects hidden in a collection of 270 haystacks. What are your odds of searching 100 haystacks (assuming that if you choose to search a haystack with an object in it, you'll find that object) without finding an object? My discrete math skillz have eroded to the point where any attempt to work this out myself yields preposterous numbers..
posted by COBRA! on Dec 1, 2004 - 30 answers

If the likelihood of event A occurring is 15%, and the likelihood of independent event B occuring is 5%, what is the likelihood of EITHER event occuring? [more inside]
posted by sohcahtoa on Sep 10, 2004 - 12 answers