For questions about probability, probability theory, probability distributions, expected values and related matters. Purely mathematical questions should be asked on Math.SE.
Questions tagged [probability]
1407 questions
9
votes
1 answer
Is there an equivalent of a Galton box for a converging probability?
This is a question about probability. The Galton box (or quincunx) uses the physical process of shot moving down a pin-board, to demonstrate central limit theorem, eg:
So I am interested in events with converging probabilities (like a coin toss @…
Frank Zafka
- 121
7
votes
3 answers
Feynman random walk
In Richard Feynman's lectures on physics, chapter six, part 3, he explains something called the random walk, in which, in a succession of trials, a system moves forward one step or backward by one step, each with probability one half.
He comes to…
6
votes
0 answers
What properties would a physical biased die have?
Imagine a physical biased six-side die. How much and what kind of bias we could possibly introduce by moving it's center of mass? What would be the exact mechanism describing the relation of center of mass and probabilities of landing on each side?…
Tim
- 161
2
votes
1 answer
Feynman's Random Walk
In chapter 6 of volume 1 of the Feynman lectures, Feynman explains the random walk. Here's the link for the lecture:
http://www.feynmanlectures.caltech.edu/I_06.html
Feynman says that there is a factor of 2 between D and NH. I dont get that.…
Osaid
- 29
2
votes
1 answer
In Feynman's "Random Walker" probability example, why is $D^2$ better for illustrating "wandering"?
Taken from Volume 1, Chapter 6, Section 3 of the Feynman Lectures on Physics.
Feynman says that in describing random, equally-probable-backwards-or-forwards motion, that,
We might therefore ask what is his average distance travelled in absolute…
bittenfig
- 31
1
vote
0 answers
How can you modify the odds of winning at a wheel spin?
So lets say you have a wheel divided in x sector
You want to rig the wheel to decrease the chances of someone landing on the green circle.
Now lets say you do it by putting magnets in the red object between each sector.
The magnets each have a…
Samuel Fyckes
- 285
- 2
- 7
1
vote
1 answer
Verifying a formula for the entropy of a system
I would like to show that the equation
$$S = -k\sum_{i = 1}^{N} p(n_{i}) \ln p(n_{i}),$$
holds for a binary system with a given definitinon of entropy.
Julie
- 79
0
votes
1 answer
Finding probability distribution of a continous random variable
How is the probability density function of a continuous random variable computed? For example, how is the Gaussian pdf for a continuos random variable computed? If you were the first one to come up with Gaussian pdf, how might you have done it?…
AI_Revolt
- 11
0
votes
2 answers
Edge distribution points evenly distributed on circle
We have a circle of radius R on which we evenly spread points. We are interested in the distribution of points by radius and polar angle that you get after transforming the even distribution of $f_X(x, y) = 1/\pi R^2$,
from cartesian coordinates (x,…
0
votes
1 answer
Trouble in assigning probabilities
Forgive me if this question is too elementary for this site, but I am wondering if there is any governing principle that guide us in assigning continuous probability distributions? I have encountered many situations where the authors assign a…
Kid
- 13
0
votes
1 answer
Average distance of a freefalling body in random intervals
This is taken from the first example in Griffith's intro to QM:
Suppose I drop a rock off a cliff of height h. As it falls, I snap a million photographs, at random intervals. On each picture I measure the distance the rock has fallen. Question:…
Addem
- 1,229
0
votes
1 answer
Empirical probability: what does it measure actually?
Empirical probability measures the probability of an event by thought experiment.
But, by doing so, what information does it want to give? The experiment is done; so how can there be probability? The probability is found by the ratio of how many…
user36790
0
votes
0 answers
What is the cause for the validity of Statistical Regularity?
My book writes:
From experience it has been observed that the value of frequency ratio gradually approaches a definite constant number when the no. of trial becomes larger & larger. This phenomenon of stability of frequency ratio when a random…
user36790
-1
votes
1 answer
Probability basic rules when additional variables are added.
I'm very new in this field but yesterday I was thinking in the following problem. Inside a black box there are ten balls five are red, and five are blue. If the balls are the same size the probability to get one red ball is 0.5, and get a blue one…
Roga Lu
-3
votes
1 answer
Do parallel universes effect my t-test results
I rolled a dice 20 times and got 6 each time. I thought the chance of this happening by chance is very low, so it is probably likely something is behind this like perhaps the dice is bias. But then i thought if there are infinit universes, it is…
Asan Ramzan
- 103