Probability Definition and 1000 Threads

  1. Addez123

    B Probability of picking one black and one white marble

    My approach is the amount of successfull options / total amount of options. I can first pick white in 3 different ways. Then black in 4 different ways 3 * 4 But I can also pick black first then white 4 * 3 Total amount of ways to pick marbles are 7 *6 So the probability is: (3*4 + 4 * 3) / (7...
  2. G

    Why is My Calculation of Φ Incorrect?

    I calculated <+|Φ> to be (1-√2i)/4√2 + (3-2i)/4√2. When I squared this I for 16/32 but this is no the right answer.
  3. Z

    I Is the calculation related to average or probability?

    Hi, I am trying to understand the calculation in the following research paper: http://cramton.umd.edu/market-design/abdulkadiroglu-sonmez-house-allocation.pdf
  4. Z

    Request to Improve the Complexity of a Probability Question for students

    Hi, I want to frame the above Probability question for computer science students. I have stated my idea above but I want to refine it so that it becomes a more comprehensive real world problem. Zulfi.
  5. S

    Ehrenfest chain transition probability

    Here is the Ehrenfest Chain that the question is talking about: I was able to solve parts 1 and 2 as shown in the image below. But I'm not really sure how I'd prove part three. Any help would be appreciated, thanks!
  6. Glype11

    B Odds of Drawing Sequence 4457: Calculating Probability

    Suppose we have a code: 4457 If these numbers are randomly drawn what are the odds of drawing those numbers? Here's my approach: The available numbers range from 0123456789 and there are four columns, minus the numbers which were drawn gives: 1/(10^4-4)~0.01% Now what about the odds of...
  7. S

    Understanding Recurrence in Probability: Solving for hN(1) and cNcN

    I set hN(1)hN(1) equal to cNcN, but I'm confused on how I'd be able to solve it and because of that I was not able to conclude that 0 is recurrent when qx/px = infinity
  8. J

    MHB Probability of Having a Totally Dominating Set (Probabilistic Methods)

    Problem: A vertex set $S$ in a graph $G$ is said to be totally t-dominating, for a positive integer t, if $|N(v) \cap S| \geq t$ for all $v \in V (G)$. Suppose that r, t, n are positive integers such that $r > 2t$ and $t \geq \frac{14}{3}\cdot ln(2n)$, and let $G$ be an r-regular n-vertex graph...
  9. Killtech

    I Probability density expansion

    This is probably a stupid question but i don't want to make a stupid mistake here, so i thought better ask: I'm starting with the simple free Schrödinger Equation ##V(x)=0## (can be 1 dim) and an initial condition where the wave function is somehow constrained to be entirely localized around a...
  10. Killtech

    I Hydrodynamic interpretation and consistency classic probability

    So back in the other thread I asked about compatibility of classical probability theory (PT) and QM – and it turns out there is no inherent reason why they need to be incompatible. Therefore I was looking for something that makes them compatible, which wasn’t easy to search for. But there seems...
  11. Addez123

    B Probability of rolling a "6" k times out of 20 rolls of a die

    The probability should be ## (1/6)^k * (5/6)^{20-k} ## But the book says the answer is : ## \begin{pmatrix} 20 \\ k \\ \end{pmatrix} * (1/6)^k * (5/6)^{20-k} ## Because there are 20 over k different sequences, but the order doesn't matter? I just don't understand why the 20 over k is there...
  12. Saptarshi Sarkar

    Probability of finding a particle in a region

    I know how to calculate the probability of finding the particle in a region by integrating the mod square of the wave function within that region. But in this question only the operator is provided but not the wave function. I am not sure how am I supposed to proceed with this problem.
  13. I

    What is the Relationship Between Probability Amplitudes and the Sum of Terms?

    I am not sure what I can do with the equation. I realize that ## \vert c_1 \vert ^2 = \vert c_2 \vert ^2 = \frac{1}{2} ## does not mean that ## c_1 ^2 = c_2 ^2 = \frac{1}{2} ## or that ## c_1 = c_2 ##, so I don't know how to use it. I think ideally I might have something like ##P = \vert c_1...
  14. S

    Probability of X: Geo Distribution with 2/3

    a. P(X = 3) = (4/6) x (4/6) x (4/6) x (2/6) = 8/81 b. X ~ Geo (2/3) Is this correct? Thanks
  15. I

    A Building a better ranking system (probability)

    Suppose we have four games and the probability that a player will win the game are as follows: Game 1: 71% Game 2: 55% Game 3: 58% Game 4: 16% Suppose player b won these games with the following percentages of time: Game 1: 100% Game 2: 96% Game 3: 87% Game 4: 67% In other words, he's a very...
  16. Saptarshi Sarkar

    Meaning of thermodynamic probability

    I was studying statistical mechanics when I came to know about the Boltzmann's entropy relation, ##S = k_B\ln Ω##. The book mentions ##Ω## as the 'thermodynamic probability'. But, even after reading, I can't understand what it means. I know that in a set of ##Ω_0## different accessible states...
  17. A

    On the width of the kinetic energy distribution of a gas

    In these lecture notes about statistical mechanics, page ##10##, we can see the graph below. It represents the distribution (probability density function) of the kinetic energy ##E## (a random variable) of all the gas particles (i.e., ##E=\sum_{i}^{N} E_{i}##, where ##E_{i}## (also a random...
  18. fRod57

    How do I predict rogue waves using simple probability models ?

    I need to predict an upcoming rogue wave or analyse old rogue wave events using simple probability models and real-time data for a physics high school project.
  19. M

    MHB Probability of the error of type 2

    Hey! :o We have data of a sample of $100$ people from a population with standard deviation $\sigma=20$. We consider the following test: \begin{align*}H_0 : \ \mu\leq 100 \\ H_1 : \ \mu>100\end{align*} The real mean is $\mu=102$ and the significance level is $\alpha=0.1$. I want to...
  20. Saptarshi Sarkar

    What Do I Calculate the Probability Of?

    I found out that the operator H is not a Hermitian operator but I didn't understand the second part of the question. What do I calculate the probability of?
  21. CaptainX

    B What is Conditional Probability and its Properties?

    1. Definition If E and F are two events associated with the same sample space of a random experment, the conditional probability of the event E given that F has occurred, i.e. P(E|F) is given by P(E|F) = (E∩F)/P(F) (P≠0) 2. Properties of conditional probability Let E and F be events of...
  22. G

    B Calculating Dice Roll Probability: Learn Basics with Frank

    Hello, I am trying to learn the basic concepts of calculating probability as it pertains to dice rolling. I have searched the internet and not been able to figure it out. If I have a regular 6 sided dice and I want to know the probability of rolling a 3, I know its 1/6 or 16.6%. This is...
  23. M

    Find the probability of a particle in the left half of an Infinite Square well

    Attempt: I'm sure I know how to do this the long way using the definition of stationary states(##\psi_n(x)=\sqrt{\frac {2} {a}} ~~ sin(\frac {n\pi x} {a})## and ##\int_0^{{a/2}} {\frac {2} {a}}(1/5)\left[~ \left(2sin(\frac {\pi x} {a})+i~ sin(\frac {3\pi x} {a})\right)\left( 2sin(\frac {\pi x}...
  24. U

    Probability generating function

    (a) I find the geometric distribution $$X~G0(3/8)$$ and I find p to be 0.375 since the mean 0.6 = p/q. So p.g.f of X is $$(5/8)/(1-(3s/8))$$. (b) Not sure how to find the p.g.f of Y once we know there are 6 customers?
  25. Killtech

    I Quantum physics vs Probability theory

    Because I do have a background in the latter it was originally very difficult for me to understand some aspects of QP (quantum physics) when I initially learned it. More specifically whenever probabilities were involved I couldn’t really make full sense of it while I never had any problems...
  26. P

    Biology Genetics Probability (Autosomal Recessive)

    I think both Jane and Bill are carriers. I'm unsure if the answer is 1/4 (25%).
  27. snatchingthepi

    I Step unclear in Peebbles' Probability Book

    If anyone could help me understand how Peebles gets from line one of the autocorrelation to the second line, I'd be most grateful. I don't understand what identity or property is being used to go from a product in the expectation value to a sum in the expectation value.
  28. K

    A Martingale, calculation of probability - Markov chain needed?

    I am trying to estimate probability of loosing (probability of bankrupt ##Pb##) using Martingale system in betting. I will ilustrate my problem on the following example: Let: ##p## = probability of NOT getting a draw (in some match) We will use following system for betting: 1) We will bet only...
  29. S

    Average speed of a probability density wave and wave packets

    Show that ##v_{av}=\frac{\hbar k_2 + \hbar k_1}{2m}## is equal to ##v_{av}=\frac{\omega_2 - \omega_1}{k_2-k_1}##. Which of the identities listed above (if any) would make the sign change between ##k_2## and ##k_1##? One can attain a "wave packet" by superposing two or more sinusoidal waves...
  30. Peter Alexander

    Probability from the tolerance of a capacitor (Gaussian distribution)

    Given the upper data, if the nominal value for capacitance is 33nF and tolerance of 20%, then values can range between 26.4nF and 39.6nF. With the bottom margin being set at 30nF, this means that the interval takes approximately 72% of all values. Is this the correct procedure to solve this...
  31. The unbelievable solution to the 100 prisoner puzzle.

    The unbelievable solution to the 100 prisoner puzzle.

  32. M

    MHB Need help with probability question. probability of dependent events.

    Would like to know what method, or distribution to use when solving a problem like this:I start from level 0. There is a probability p chance to drop to level -1 and a (1-p) chance to increase to level 1. The levels range from level -n to level n. When it reaches level -n or level n, it resets...
  33. Biochemgirl2002

    Calculating general normal random probability

    a) P(X<18) = (18-20)/sqrt25 =-2/5 =-0.4 then you use the standard normal table and find that; P(X<18)=0.3446 b) P(X>27) = (27-20)/5 = 7/5 = 1.4 P(Z>1.4) =P(Z<-1.4) =0.0808 C) =(13<X<23) =13-20/5 , 23-20/5 =-7/5 , 3/5 =-1.4 , 0.6 P(Z<0.6)-P(Z<-1.4) =0.7257-0.0808 =0.6449
  34. Monoxdifly

    MHB [ASK] Probability of Getting the Main Doorprize

    There's an event which is joined by 240 members. The Event Organizer prepares 30 doorprize with one of them being the main ones. If Mr. Aziz's family has 15 tickets, the probability that Mr. Aziz gets the main doorprize is ... A. 1/16 B. 1/8 C. 1/4 D. 1/2 I thought the answer was 15/240 (the...
  35. S

    Probability of a fluctuation/entropy decrease

    Suppose we have a gas in the room at some temperature which is room temperature or higher. In some references the probability is given by -ΔS, which is indeed a tiny number and makes sense. However, in other references the probability is given by the Boltzmann factor plus the number of...
  36. S

    Calculating Probability of Choosing Vowels: Common Mistakes and Solutions

    My attempt: case 1: get one vowel (A) from word HOORAY = 1/6 x 2/3 x 4/5 = 4/45 case 2: get one vowel (A) from word MATHS = 3/6 x 2/3 x 1/5 = 1/15 case 3: get two vowels (2A) from word HOORAY and MATHS = 1/6 x 2/3 x 1/5 = 1/45 Total probability = 8/45 Answer key = 1/3 Where is my mistake...
  37. srallaba

    B Probability of spin in the +x direction

    Consider a qubit. Given a state equation, how to calculate the probability of finding spin in +x direction?
  38. L

    MHB Compute probability closeness between points in a 2D surface

    Hi all, Sorry, in my first message, I posted this question in the Basic Probability section, and so I moved it to this section. I have a surface (for example, a blank paper). In this surface, I have some elements of the set "A" randomly distributed. In this surface, I also have some elements...
  39. megf

    I Probability Density Function of the Product of Independent Variables

    How do I find the probabilty density function of a variable y being y=ab, knowing the probabilty density functions of both a and b? I know how to use the method to calculate it for a/b - which gives 1/pi*(a²/b²+1) - using variable substitution and the jacobian matrix and determinant, but which...
  40. Philip Koeck

    A The probability of finding R out of N bosons in one half of a volume

    For the probability of finding R out of N (indistinguishable) bosons in one half of a volume with a total of 2g states (g in each half) I get the following expression: PR = WR / WT where WT is the number of ways of distributing N particles in the total volume: WT = (N+2g-1)! / (N! (2g-1)!)...
  41. Biochemgirl2002

    What Are the Tests for Independence in Probability Statistics?

    A) (0.5)-(0.3) =0.2 b) c) i have no clue how to determine from just a set of numbers if they are independant or mutually exclusive
  42. S

    MHB Probability calculation of dependent events with limitations

    Dear forum, First time posting and as English is not my native language, I'd like to apologize in advance for any linguistic errors I make. Yesterday, I received a case which sounded really easy to calculate but for some reason I can't get my head around it. This is the case: In a shipping...
  43. Haynes Kwon

    I Probability flux inside the finite potential barrier

    In Bransden textbook, it is stated that the probability current density is constant since we are dealing with 1-d stationary states. It gives probability flux outside the finite potential barrier which I verified to be constant with respect to x, but it doesn't provide the probability current...
  44. S

    MHB Maximizing Probability of Finding Explosive Device in Bounded Domain

    I am trying to solve the following problem. Let us take a bounded domain $S$ in which an explosive device is located. A team is deployed to locate and disable the device before a certain time T (when the device explodes). There are several criteria to be satisfied: 1. The domain $S$ is...
  45. warhammer

    Question on Quantum Physics- Probability of finding a particle

    I calculated the complex conjugate of both the given wavefunctions. For ψ1: ∫re^((-2)mod(r)x)dx=1 with upper limit ∞ & lower limit -∞. I replaced the upper and lower limit after breaking down the function inside integration as follows- r*∫e^(2rx)dx from -1/r to 0 and r*e∫e^(-2rx)dx from 0 to...
  46. M

    MHB Solving 2 Problems with Exponential RVs: CLT & Probability

    I have the following two problems that I need to solve: 1. Suppose that the service time for a student enlisting during enrollment is modeled as an exponential RV with a mean time of 1 minute. If the school expects 500 students during enrollment period, what is the probability that the...
  47. P

    I Do These Probability Conditions Imply Independence of Events A, B, and C?

    Hello everyone. Let us consider 3 events A,B,C such that: $$P((A \cap B )\cup C)=P(A)*P(B)*P(C)$$ Notice that the second term is a union and not an intersection. Are they independent? And what if the assumption was: $$P(A \cap( B \cup C))=P(A)*P(B)*P(C)$$? I know that the independence condition...
  48. Wi_N

    I I have a real-life Probability problem

    I'll try to keep this short. Kazakhstan just hosted the world championship wrestling tournament and I noticed that they did exceptionally well this time around, hometown psychological advantage aside they finished in 2nd place. Last year they finished 13th in Budapest. So immediately I knew...
  49. jaumzaum

    Is symmetry necessary for solving triple integrals in probability calculations?

    I just started learning triple integrals. I don't know if this is right (I'm only concerned about the limits of the Integral) Consider the case ## a>=b>=c ## $$ P = \lim_{M \rightarrow +\infty} \frac { \int_{a=0}^M \int_{b=\frac a {1.1}}^a \int_{c= \frac a {1.1}}^b \, da \, db \, dc} {...
  50. ckirmser

    Question on Probability - been way too long since college

    Summary: Probability of an event based on a data table Good morning, all - I'm working on a question involving obesity based on alcohol and tobacco consumption. The question is based on a table with five variables; • (age) An age group (10-25, 26-50, 51-75, 76+) • (alc) An alcohol...
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