43 posts tagged with math and probability.
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How to maximize my chances of passing?
Does anyone have any tips or tricks for making the most out of my study time and/or keeping myself in the right headspace for exams for a must-pass class? [more inside]
Math: Probability and combinatronics
Ok... so I'm looking at a candidate for a job position and I notice on his resume the following:
Between his mobile number and my mobile number (10 digit, US format) there are 9 numbers in common, 5 of which are in the right position. [more inside]
How to calculate probability three things will be on same day of week?
If I know Event 1 will happen three times in a week, Event 2 will happen four times, and Event 3 twice, how can I tell how likely they will be to happen on the same day (assuming they're random)? [more inside]
Real-life based math problem
On my daily commute back home, I drive past ~15 gas stations. In my country, gas prices change daily and vary a bit from one station to the next. So that got me thinking: What would be the best method to decide whether to fill your tank on the station you're currently in front of or lose the current price forever and take your chances on the remaining stations? Assume each station sets their daily price randomly (but they are all within a $1 range), and we start with the reference of the price we paid last time.
Note: I can easily keep track of the lowest price on my way to work and then fill up on the way home, but I am more interested in the math problem than the practical issue.
Help me figure out what's up with this probability question
Someone posted a probability question on Mastodon: "A, B and C toot the truth with a probability of 1/3 and lie with a probability of 2/3. A makes a toot and B toots an observation on whether or not A was tooting the truth or not. C toots that B confirmed A was truthful. What is the actual probability that A's toot was truthful?" Either I made it more complicated than it needs to be, or a lot of other people are wrong, and I suspect the former. Help me get to the bottom of this! [more inside]
Is This Bathroom Occupied?
The other week there was a puzzle on FiveThirtyEight about the probability of the sign on a bathroom being correct given the behavior of different people in an office (solution). Can you help me figure out why my approach doesn't work? [more inside]
Too Many Strata To Sample
I have multiple independent variables that I want to stratify my sampling across, but the result would be way more strata than I can sample. Is there a way to stratify across different character states for each independent variable without creating strata for the interactions of each? Example inside. [more inside]
Can you figure out the probability of a specific outcome?
I work in a field where we think about possibly dangerous people. If Mr. X is a poor driver and has a 5% chance of running a red light in the next month, can you know the probability of him running a red light at a specific intersection? Can you know a range of probabilities for that specific intersection? What if it's the intersection that he drives through most often? I think this likely has an easy answer but none of us can clearly explain it so we keep talking about it.
Statistical framing of the engineering and extremism article
Reading this article on the blue got me thinking about conditional probabilities, prediction and causality. I came up with an analytical framing of what I think the article is saying and would be grateful if stats/social science Mefites could tell me if it seems accurate or else set me right. [more inside]
How to Math
I'm a computer science major in college. I'm not a freakin' genius, but I do well-- get A's in my classes, good with abstraction (e.g. pointers), etc. However, I seem to have missed... my entire high school pre-Calculus math curriculum? I don't know. [more inside]
Probability distributions and their practical applications
I am looking for a resource that lists probability distributions and their common real-world applications. For example, I'd expect to see: Lognormal - daily returns in the stock market. Poisson - failure rates for mechanical equipment, ... [more inside]
Math Problem
Please help with this probability related math problem. [more inside]
2 problems of combinations and permutations.
How many unique ways are there to put X rocks into Y boxes?
(Given two different sets of attributes for both the rocks and the boxes.) [more inside]
Chance of event with small sample size, based on larger related sample?
Can/how can one improve the estimate for a chance of an event with a small historical sample size by utilizing the chance of a related event with a large historical sample size? Example and half-assed guess inside. [more inside]
The Gambler's Fallacy, of course. But maybe...
A coin flips three times and comes up heads 2/3. Not suspect.
But a coin flips 100,000 times and comes up heads 2 out of 3 times, that starts to look fishy. The standard probability of this is always roughly 50-50, but assuming a 2/3 ratio pointing to a "rigged" coin, how could you plot the increasing likelihood that a given coin is rigged? [more inside]
Bad at math
I have a question about probability math. I am essentially flipping a coin (except instead of a 50/50 chance, my odds are 50.5% heads, 49.5% tails).
I am concerned with the probability of me hitting heads (a 50.5% chance) several times in a row. [more inside]
Probability and a rather unique deck of cards.
Each card in a certain deck has three letters on it.
The first letter is either A, B, or C.
The second letter is either D, E, F, or G.
The third letter is either H, I, J, K, or L.
Every possible combination is represented exactly once in the deck. Ergo, there are 3x4x5=60 cards in the deck.
How can I determine the probability that a hand of X cards, drawn randomly from the deck, will include at least one of each of the letters?
What does a professional statistician do?
(Good) jobs involving probability and statistics other than math teacher or actuary? [more inside]
How to solve a complex statistics problem with a script?
In this game, you roll a number of six-sided dice to get a total. The total is either the highest single die result, or the sum of any multiples rolled, whichever is higher.
For example: If I roll three dice and get a 3, 4, and 6, my total is 6. But if I roll a 4, 4, and 6, my total is 8, the sum of the two 4s.
What I want to find out is the mean, median, mode, and standard deviation of the possible totals given N dice. How might I create a simple script to compute this? [more inside]
Practice Probability Word Problems
What great books or resources are there for practicing probability word problems such as for standardized tests like the GRE? [more inside]
What are the odds that two randomly selected people share the same bank PIN?
Statisticsfilter: Given available information about the distribution of self-selected 4-digit passwords (specifically banking PINs), is it possible to calculate the probability of two randomly selected individuals having the same PIN? If so, what're the odds? [more inside]
How do I calculate the probability of a specific sum of repeated die rolls?
I'm looking to learn how to calculate probabilities for a multi-round dice game. I've researched this question some, and it looks like I might need to know how to use the multinomial distribution, but I can't find any good introductions. Please point me to the most layman-accessible educational material on this subject, and help me to help myself. [more inside]
Gambling odds question
How would one (legally) take advantage of the change in odds of a given NFL team to win the Super Bowl? [more inside]
What are the odds?
Math/probability not sports: I am not a gambler, but I am trying out a method of betting on sports with some initial success. At what point can I use the numbers to confidently assume that this is down to the system rather than luck? [more inside]
Thirsty work
Mathfilter. Bonus: involves football and beer [more inside]
Probability Question
Probability Question [more inside]
Need help with a probability question
Can someone help with a probability question? [more inside]
Straightforward Dice Probability
Please refresh my memory with regard to a straightforward question of fair dice and probability. [more inside]
Help me learn to figure out dice probability for games
Help me teach myself enough about probability to properly balance the board game I want to design. [more inside]
Conditional Probability
Stats-filter: Given a binary matrix, if I know the total number of ones in a given row and a given column, can I calculate the probability that a given position contains a one? [more inside]
How many songs do I have to listen to before I start again?
Can you help me figure out this math question related to probability? [more inside]
Teach me about this thing you call "math"...
Here's an obnoxious school question that's been nagging me for days:
Suppose that the height (at the shoulder) of adult African bull bush elephants is normally distributed with µ = 3.3 meters and ∂ = .2 meter. The elephant on display at the Smithsonian Institute has a height 4 meters and is the largest elephant on record. What is the probability that an adult African bull bush elephant has height 4 meters or more? [more inside]
Math and Odds and Blackjack
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]
Probability question (in need of code)
It's late, I'm tired, and I have a probability and coding question that's fairly simple. [more inside]
How to calculate probability of being dealt certain cards?
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]
complex dice probability make head esplode
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]
How many rolls 'till n values in a row.
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]
Infinite vs Infinite
ProbabilityFilter: Calling all mathematicians... [more inside]
Looking for help with a question of probability.
MathFilter: Okay, I've got this gumball machine, which contains an infinite amount of gumballs, evenly distributed between 100 different flavors... [more inside]
Binomial distribution comparison
Probability of one binomially-distributed variable being greater than another one - is there a closed form for this? [more inside]
Deriving formulas for Weibull distributions
Probability: A coworker is having an issue with deriving a few formulas for a Weibull distribution. Any pointers? [more inside]
What are the odds of finding 20 needles in 270 haystacks?
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..
Probability calculations
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]
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