Probabilities Definition and 398 Threads

This seems like a simple matter, but apparently it is controversial: Is it meaningful to talk about probabilities for temporal uncertainty? If I find myself in a room without a clock, I might wonder what time it is. I know that I entered the room at 9:00, so it has to be later than that. I know...

Let me explain myself. In the roulette game, you can bet on dozens, that means, betting to 12 numbers which are placed separately along the wheel. (12 out of 37 total numbers). But I had this curious doubt. if you bet on a sector of the roulette, composed by 12 numbers... the likelihood is...

I heard about quantum physics describing it but can anyone make it clear to me??

Homework Statement the administration council of one industry is composed by 7 people 4 mens and 3 womens. an election its hapening to vote chairman and secretary, if all members of the council are candidates obtain the follow a) just mens take positions b) a chairwoman elected C) at least one...

First post and I'm wondering if I could get some help. I'm new to queueing theory so I'm not sure how to solve this problem. Population-------------> Queue--------------> Server I have a calling population that is infinite or a vast amount. The queue capacity is limited at 13. There is 1...

If I understand the many worlds QM interpretation correctly, for every quantum event the universe divides. However not all quantum events have a 50/50 probability. How does the many worlds interpretation deal with quantum events that have,say a 1/3 2/3 probability split?

This paper https://arxiv.org/abs/quant-ph/9911101 says this: If we normalize those terms, don't we get 1/4 , 1/2 , 1/4 as the probabilities, since ##|HT\rangle## and ##|TH \rangle## are indistinguishable?

Homework Statement Basically, I'm dealing with part d) in this document: https://s3.amazonaws.com/iedu-attachments-message/b663095a5021cb6aee55657de728a8d7_bfbe0ba9d2f10f8ac9ef9d049934c1da.jpg. I have found that the angular momentum only depends on spatial coordinate and it doesn't on time. Is...

I am perplexed because it seems that I have come up with a system for beating the roulette which has a positive mathematical expectancy/hope... but only in the calculations, which I think that I've made wrong. So I want to know in what I have failed doing the calculus. Well basically the method...

According to WKB approximation, the wave function \psi (x) \propto \frac{1}{\sqrt{p(x)}} This implies that the probability of finding a particle in between x and x+dx is inversely proportional to the momentum of the particle in the given potential. According to the book, R. Shankar, this is...

This probably has been asked before but I didn't find it. As I understand it with the Many Worlds Interpretation of quantum mechanics, a different "world" exists for each outcome. I have read about the an issue regarding probability outcomes within a world but cannot remember the answer. The...

<Moved from a technical forum, therefore no template> For two non-interacting fermions confined to a 1d box of length L. Construct the antisymmetric wave functions (Slater determinant) and compare ground state energies of two systems, one in the singlet state and the other in the triplet state...

Homework Statement f(xy)=49/8*e^(−3.5*y) 0 < y < inf and −y < x < y 0 otherwise a. Find the marginal probability density function of X, fX(x). Enter a formula in the first box, and a number for the second and the third box corresponding to the range of x. Use * for multiplication, / for...

Hi! I have a question regarding making the transition matrix for the corresponding probabilities. The main problem I feel I have here is figuring out how to represent the probabilities in the question in the transition matrix. Like if something is 7 times more likely than something else.. Any...

Homework Statement Each week, Stéphane needs to prepare 4 exercises for the following week's homework assignment. The number of problems he creates in a week follows a Poisson distribution with mean 6.9. a. What is the probability that Stéphane manages to create enough exercises for the...

Homework Statement Consider a system consisting of a single hydrogen atom/ion, which has two possible states: unoccupied (i.e., no electron present) and occupied (i.e., one electron present, in the ground state). Calculate the ratio of the probabilities of these two states, to obtain the Saha...

Homework Statement The spin components of a beam of atoms prepared in the state ##|\psi_{in}\rangle## are measured and the following experimental probabilities are obtained, $$P_{+}=\frac{1}{2}, \quad P_{+x}=\frac{3}{4}, \quad P_{+y}=0.067$$ $$P_{-}=\frac{1}{2}, \quad P_{-x}=\frac{1}{4}, \quad...

Homework Statement Four distinguishable particles move freely in a room divided into octants (there are no actual partitions). Let the basic states be given by specifying the octant in which each particle is located. 1. How many basic states are there? 2. The door to this room is opened...

This was off-topic in the thread on vacuum fluctuations where the quote appeared, so I opened a new one. I didn't know the paper before, so first need to read it...

I have two questions about the use of stochastic differential equation and probability density function in physics, especially in statistical mechanics. a) I wonder if stochastic differential equation and PDF is an approximation to the actual random process or is it a law like Newton's second...

Homework Statement i'm having trouble coming up with an equation for this problem [/B] Mulder and Scully agree to meet at the FBI lobby sometime within a period of N minutes (e.g. 40 minutes). Each of them may show up anytime during that period (with a uniform distribution). If Scully arrives...

Hi there. Excuse that I write it all in standard text but I don't know how to write it otherwise. I'll get right to the question and try to see if I understand the theory from the answer. Suppose we have a system of two electrons, one spin up and one spin down in a system with 3 possible...

Please read this Insight here: https://www.physicsforums.com/insights/quantum-amplitudes-probabilities-epr/

The question asks: A physical device can be in three states: A,B,C. The device operates as follows (all time units are in hours): The device spends an exponentially distributed amount of time in stateAA (with mean of 12minutes) and then with probability 0.6 goes to state B, and with...

So the problem asks: A computer server runs smoothly for Exp(0.2) days and then takes Exp(0.5)days to fix. The server is running fine on Monday morning, t=0. Find the probability that the server was fixed at least once (i.e. at least one complete repair was done) in the next 7 days and the...

Homework Statement Roll a fair die 5 times, find the probability that the first two rolls have the same outcomes. Homework EquationsThe Attempt at a Solution The total outcomes is 6^5, I think we have 6^2 * 6 choose 2 /6^5 since the first two numbers are fixed and we can choose 2 numbers from...

Homework Statement Let Y_1,Y_2 be independent random variable with uniform distribution on the interval [1,2]. Define X=max{Y_1,Y_2}. Find p.d.f., expected value and variance. Homework EquationsThe Attempt at a Solution Since $X=\max\{Y_1,Y_2\}$, this tells $Y_1$ and $Y_2$ must at most $x$...

There are two boxes. Box I contains 5 red balls and 4 white balls. Box II contains 3 red balls and 6 white balls. A ball is taken randomly from box I and put into box II. Then, from box II, two balls are taken randomly. What is the probability of both balls taken from box II are red? I only...

Homework Statement The operator for the momentum of a particle in 1D is ##\hat{p}_x = -i\hbar\frac{d}{dx}## has the eigenfunction ##\psi(x) = e^{ikx}##. The Schrodinger equation for a free particle in 1D is ##\frac{-\hbar^2}{2m}\frac{d^2\psi}{dx^2} = E\psi## Which has the solution ##\psi(x) =...

Hello. Given a range of time in which an event can occur an indefinite number of times, we say a random variable X folows a poisson distribution when it follows this statements: X is the number of times an event occurs in an interval and X can take values 0, 1, 2, … The occurrence of one event...

hey, this thread might be a bit longer, but I have already calculated everything and I am quiet sure that it is right :) Just need someone who confirms me or not :) 1. Homework Statement Time evolution of probabilities. An electron inside a quantum well of length L is at time t = 0 in the...

I hope this question is in the right place. I'm trying to calculate probabilities and struggling. Hopefully someone can help. Suppose I want to calculate the probability of N being a product of a prime below sqrt N. N will have a 1:2 chance of being a product of 2. If N is not a product...

A code is generated consisting of 3 letters followed by 2 digits. Each of the 3 letters generated is equally likely to be any of the 26 letters of the alphabet. Each of the 2 digits generated is equally likely to be any of the nine digits 1-9. Find the probability that a randomly chosen code has...

So I'm a bit confused about the properties of wave mechanics, and trying to understand certain phenomena, which may be talked about, but I've never seen anyone talk about it. Here is the example. We have a bowl of water, a stick and a ball. We start with the ball, in which we drop it into the...

Homework Statement This problem is from Zetelli 3.21 http://imgur.com/wYTNVwz http://imgur.com/wYTNVwz Homework Equations Just the standard probability via product between the eigenfunction and the wavefunction The Attempt at a Solution I've found the eigenvectors for the Hamiltonian...

I'm trying to figure out how to correctly workout the probability of rolling 3 6's if I roll 4 dice at a time. If I roll 3 sixes in a row, I don't bother with the last roll The order in which I roll them doesn't matter So here are my potential combinations Combination 1 => x 6 6 6 Combination 2...

There is a card game where one player gets three cards and only uses two (the third one is discarded without showing to an opponenet), and the second player gets also three cards and uses only two, discarding the third card in the similar way - without showing. I am trying to enumerate all...

Consider two polarisation-entangled photons A and B fired at two polarisationfilters that are at a certain angle α. Are the probability that A is passing its filter and the probability that B is passing its filter indepedent probabilities? I am aware that is probably an incredibly stupid...

Hello Physicsforum Homework Statement I have a problem proving this: Given C(x)=[0, 3/x] for all x\in\chi, with \chi=\Omega being the sample space and P_q=Geom(q) being the geometric distribution. I have to show that C(x) is a confidence Interval for q but I don't know how to get started...

Is there a closed form expression for the sum: Σx2/n! from 0 to N for N=∞ it is an exponential but what about the finite case?

Homework Statement There are ##N = 10000## clients of an insurance company. One-half of them will file claims with probability ##p_1 = .05##, another half of them will file claims with probability ##p_2 = .03##. Each claim is worth ##$1000##. Find the Value-at-Risk at the level α = 0.99, that...

Homework Statement The state of Oregon wishes to design a new lottery game with the following rules:  1.Each ticket costs $5  2.There will be three prizes: $10, $100 and $1000  3.The probability of the $10 prize will be 20%.  4.The probability of the $100 prize will be 1%  5.Ten thousand...

Let ##X_i## are i.i.d. and take -1 and +1 with probability 1/2 each. How to prove ##\lim_{n\rightarrow\infty}{\sum_{i=1}^{n}{X_i} }##does not exsits (even infinite limit) almost surely. My work: I use cauchy sequence to prove it does not converge to a real number. But I do not how to prove it...

Homework Statement Suppose that two measurements are made on a qubit in rapid succession. The first is δz and the second is δn. Suppose the first results is always +1. Calculate the probabilities of obtaining the results +/- 1 for the second measurement in terms of the angle θ between z and n...

The Question Let X and Y be two independent Geometric(p) random variables. Find E[(X^2+Y^2)/XY]. Formulas Px(k) = py(k) = pq^(k-1) E(x) = Σx(p(x)) My attempt at a solution I am really struggling with this question because I want to apply the LOTUS equation but am unsure how to do it for...

Homework Statement It is a potential barrier with E of the incoming matter wave E>U (greater than the height of the barrier). I have already done a LOT of algebra to get to the point where ##\frac{F}{A}=\frac{2kk'e^{-ikL}}{2kk'cos(k'L)-i(k'^{2}+k^{2})sin(k'L)}## which I won't bother writing...

"An internal study at Lahey Electronics,a large software development company,revealed the mean time for an internal email message to arrive at its destination was two seconds. Further, the distribution of the arrival times followed a Poisson distribution. a.What is the probability a message...

could we say like the title that if we throw coins n times the result were s=nhead/n this were statistics and we could find a prediction for the next toss p(s)=? I thought we could reason like : the next tosses shall equilibrate towards 1/2 so for example p(s)=1-s ?

I'm looking for a way to calculate the probabilities of Archimedean Solids landing on a specific face if a person would roll one. Of course, not the regular polygons like cubes and dodecahedrons, but something with more than one type of face like the snub cube or truncated icosahedron. I am...

Is there something wrong with negative probabilities per se? I don't what to hear that they are "unphysical" because it is not clear what reality is. Can negative probabilities (or probabilities > 1) be somehow consistent with macroscopic realism => not causing any macroscopic weirdness (no...