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Questions tagged [probability-distributions]

Questions on using, finding, or otherwise relating to probability distributions, probability density functions (pdfs), cumulative distribution functions (cdfs), or other related functions. Use this tag along with the tags (probability), (probability-theory) or (statistics).

Any probability distribution, including beta, binomial, chi, Erlang, gamma, geometric, lognormal, negative binomial, normal (Gaussian), Pareto, Poisson, Student's t, uniform, Wald, Weibull, zeta, and Zipf.

28080 questions
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Quotes for statistical game

I have a simple scenario that displays quotes on a page. These quotes are numbers which players can choose, if certain events happen the player wins these quotes. Now the quotes for this scenario are based on soccer players and specifically the…
Roger Far
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Bullseye distribution (Rayleigh distr)

Does anyone know what bullseye distribution is? It should be a special case of Weibull distribution, but I haven't found any useful information after googled it. Just for information, I heard this term from a german. So it could be some uncommon…
newbie
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Multivariate normal and multivariate Bernoulli

Say I only have the mean vector and the covariance matrix of some multivaraite distribution X, where all single-variable marinals are normal (note: this is not generally a multinormal distribution). Is there some maximum distance, measured perhaps…
Omri
  • 699
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Relation between Weibull and exponential distributions

The probability distribution function of a Weibull distribution is as follows: $$ f(x) = a\cdot b^{-a}x^{a-1}\cdot e^{(-x/b)^a},\quad x>0 $$ for parameters $a,b>0$. I have to show that $X\sim\mathrm{Weibull}(a,b)$ iff $X^a\sim\mathrm{expo}(b^a)$.…
Way to infinity
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probability distribution with discrete random variable

I have tried it out, but finding it difficult to post them in proper format. Please help me with the solution.
manayay
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poisson random variable distribution using probability

Let $X$ be the number of emails that a company receives in a day. Assume that $X$ is a Poisson random variable with parameter $\lambda$. The company classifies each email as spam or not spam. The probability that a single email is spam is $p$. Let…
manayay
  • 297
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How to change variables of a probability distribution when variables have different dimensions

Is this even possible? Say I have a pdf $p(x,y\mid\phi)$, and a function $z = f(x,y)$. Is there a way to derive $p(z\mid\phi)$? The usual change of variables rule $$p(z\mid\phi) = p(x,y\mid\phi) ~\left \lvert \frac{d(x,y)}{dz} \right…
ratsalad
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Marginal Density - Probability

(X,Y) is a two-dimensional abolute continuous random vector with the density function fx,y given by: (1) $f_{X,Y}(x,y) = \begin{cases} \frac{1}{2} & 0 \le x \le 1, 0 \le y \le 4x \\ 0 & \text{otherwise} \\ \end{cases}$ Show the density functions…
mathIsHard
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How would I go about finding an explicit formula for c given a and b?

Apologies if I am missing something obvious. I am an undergraduate Physics major just messing around with numbers in my free time. For fun, I was trying to see if there was a way to explicitly calculate the probability of rolling a particular sum on…
Curious Cube
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If $X$ and$Y$ are independant random variables and $U = X+Y$, $V = -\log(X/(X+Y))$, are $U$ and $V$ independant?

Let $X$ and $Y$ be independant exponential random variables with parameter $\beta$ = 1. Let $U = X+Y$ and $V = -\log(X/(X+Y))$ Are $U$ and $V$ independant? There's similar questions I found on here but $V$ is $X/(X+Y)$, I don't understand whether…
tsasinc
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3 answers

Probability to roll a sum of less than 3600 with 1000 dice throws

I try to estimate the probability that the sum of the numbers when rolling a die 1000 times is less than 3600. I am confident that I can approximate the probability with a normal distribution with expectation value $\mu=3500$ and the correct…
Rüdi Jehn
  • 594
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drawing at least one colored ball of each from urn in a case of large populations

My problem is: If an urn contains balls of $10^7$ different colors, namely $K_1, K_2, \ldots K_{10^7}$, and there are 1000 balls of each color, so that the total number of balls in the urn is $10^{10}$, then if I draw $10^8$ balls, how do I…
Danny Bennett
  • 31
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drawing different colored balls from one urn without replacement and at least

I have this problem (numbers in the example are much smaller than reality, so it would help to get a general equation): One urn contains $10$ red, $10$ yellow, $10$ black, $10$ green, and $10$ orange balls (total of $50$). Question 1: if I draw an…
danny bennett
  • 29
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Reciprocal Shifted Log-Normal Distribution

Let $X$ be a log-normal distribution, let $k\geq0$ be a real value and let $Y=\frac{1}{X+k}$. What is the name of the $Y$ distribution other than 'reciprocal shifted log-normal'? What is the mean of $Y$ in terms of $X$'s mean and variance? Thanks!
questiondude
  • 199
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Find the probability distribution.

A game is to choose a random real number $x$ between 0 and 10. The earnings are given by $|5-X|$ being X the number chosen. (a) - Find the earning distribution and (b) - If you play twice with $X_1$ $X_2$ and $X = max\{X_1,X_1\}$, what it's the…
Cure
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