A message from our CEO about the future of Stack Overflow and Stack Exchange. Read now.

# Questions tagged [probability]

For basic questions about probability and for questions about calculating a probability, expected value, variance, standard deviation, or similar quantity. For questions about the theoretical footing of probability (especially using [tag:measure theory]), ask under [tag:probability-theory] instead. For questions about specific probability distributions, use [tag:probability-distributions] instead.

74,917 questions
Filter by
Sorted by
Tagged with
28 views

11 views

### Question regarding determination of density function, if it's given as a function of $x$ multiplied by some constant C.

So, I need to determine whether a function can be a density function of some variable $X$. Do, I simply assume first, that it is and find $C$ by integrating it and equating the expression to 1 and ...
17 views

### $X$- amount of experiments conducted until certain number of coloured balls is pulled out. Write an distribution of $X$

Given that in the box there are $4$ white and $4$ black marbles and that $4$ marbles are randomly selected and then put back into the box, what is the distribution $X$ if the experiment is conducted ...
151 views

### Why are all subset sizes equiprobable if elements are independently included with probability uniform over $[0,1]$?

A probability $p$ is chosen uniformly randomly from $[0,1]$, and then a subset of a set of $n$ elements is formed by including each element independently with probability $p$. In answering Probability ...
17 views

### Joint Distribution of Scaled multivariate Standard normals

Let $X$ be $N(0,I_n)$, a $n$-dimensional multivariate standard normal. Let $Y = X/||X||$. I know $Y$ is distributed uniformly on the surface of a $n$ dimensional "circle" but how do I prove this? The ...
65 views

27 views

### Expected number of siblings in a family [duplicate]

The question goes as follows: Given a family where the number of children is a random variable $(\mu=1.8, \sigma=0.36)$, if one selects a child randomly, what’s the expected number of siblings the ...
18 views

### Do you know any literature on this mathematical model of aggregation?

I'm currently studying a fun and very simple mathematical model of particle aggregation presented in this 1988 article of Hideki Takayasu, Ikuko Nishikawa, and Hal Tasaki. Here is a presentation of ...
18 views

### Calculate Probability of 3 out of 25 boxes have 1 out of 5 reds [closed]

We have 25 boxes, 5 red balls and 20 green balls. I will pick up 3 boxes in random order. What is the probability that 1 red in 3 boxes? 2 reds in 3 boxes? 3 reds in 3 boxes?
58 views

### Probability of an event if r out of n events were true.

I need to calculate what is the probability that the next event will be true if r out of n events were true. It is given that the probability for all events is equal and the probability is evenly ...