Random Definition and 1000 Threads

Homework Statement Hi, at the moment I am trying to revise for my Probability exam, and a couple of the questions on the past paper are as follows, however I can find nothing in our notes that is of any use! Any help would be greatly appreciated, thankyou. i) Two random variables X and Y...

hello! i'm planning to build such a generator, but i have some questions: 1. what dimensions and materials are needed to shield one typical geiger-muller tube from the background radiation? 2. even with the complete protection, is it possible that the counter tube will trigger without...

Hello, How do we interpret the fact that a random variable can have no mean? For example the Cauchy distribution, which arises from the ratio of two standard normal distributions. I seek intuitive explanations or visualisations to understand math "facts" better.

I am trying to create 2 list of random numbers of the same length The 1st list random list i can do RandomIntegerRandomInteger[{1, 7}, 10] to get {6, 5, 4, 7, 2, 1, 5, 5, 2, 6} the 2nd list however i want 10 numbers from 1-30 that are all different and in order, what do i need to add to...

Hi. I'm being asked to generate a random number either 0 or 1 and then to randomly allocate this 0 or 1 to one of 100 groups, and then to repeat this many (a million) times. So... I can easily generate randomly either a 0 or 1 by randint(1), but how do I randomly allocate this to 1 of 100...

Suppose X and Y are independent Poisson random variables, each with mean 1, obtain i) P(X+Y)=4 ii)E[(X+Y)^2] I m trying to solve this problem but have difficulty starting ... If some one could give me a some pointers

Question : Random variate X follows a normal distribution with mean 0 and variance 1 i.e.X~N(0,1). Given Y = 2X + 4, find i) E[Y] ii) Var(Y) iii) E[X^3] Solution: here E[X'] = 0 and V(X) = 1 i) E[Y] = E[2X+4] = 4 [Is this correct] ii) Var(Y) = E[Y2] - [E(Y)]2 =E[Y2] -16...

Suppose that a person chooses a letter at random from "RESERVE" Question : Suppose that a person chooses a letter at random from "RESERVE" and then chooses one at random from "VERTICAL" . Find the probability that the same letter is choosen. Solution: Probability of choosing letter from...

Here's my dillemma: I'm writing up a spreadsheet where we have 100 passengers on a plane. Excel randomly generates their assigned seat, and the seat they end up taking. But the problem is, I need to make it so that Excel does not generate the same number twice.

Question : Let xi, where i = 1,2,3,..,100 be indepenedent random variables, each with a uniformly distributed over (0,1) . Using the central Limit theorem , obtain the probability P( <summation> xi > 50)

Question : The mfg of a random variate X is given by Mx(t) = 0.8 et + 0.2)11 i) Find the P(x>0) ii) Find E[x2]

Let Xi, i=1,...,10, be independent random variables, each uniformly distributed over (0, 1). Calculate an approximation to P(\sumXi > 6) Solution E(x) = 1/2 and Var(X) = 1/12 [How should is calulate the approxmiate ]

Hi everyone, here's a probability problem that seems really counter-intuitive to me: Find four random variables taking values in {-1, 1} such that any three are independent but all four are not. Hint: consider products of independent random variables. My thoughts: From a set perspective...

Problem: Consider a random sample n from a population with probability distribution f(x,p) that depends on parameter p. Find the maximum likelihood estimator for p when f(x,p) = p^x (1-p)^1-x for x=0,1

Hi, everybody. My problem is about Probability and Random Process. i can't understand the probability density function of sum of two random variables and function of product of two random variables. Here is my question with a part of a solution: how can i find these problems solutions and...

Homework Statement 1. Let X , Y and Z be independent random variables, uniformly distributed on the interval from 0 to 1. Use Theorem 3.8.1 twice to find the pdf of W = X + Y + Z . Thm. 3.8.1 States: If X & Y are continuous random varibles wth pdfs fx(x) and fy(y), respectively then...

Homework Statement The expectation value of the sum of two random variables is given as: \langle x + y \rangle = \langle x \rangle + \langel y \rangle My textbook provides the following derivation of this relationship. Suppose that we have two random variables, x and y. Let p_{ij}...

I've sent a few emails to someone, and in their reply in my inbox, the email address would show up in the From column. But in their latest reply, their full name showed up. Why is that? I didn't add them as a contact either.

Hello I am trying to find an analytic expression for the probability that a particle will have passed a position x after a time t. It is a 1D random walk, the probability distribution after time t that a particle will end at position x is given by a gaussian, but I need to know how many...

Since current is charge flowing in a circuit, I was thinking this silly :P thought. If you are holding a charged object in your hand and you spin your hand in circular motion. Is there a current? also... If you setup a simple circuit with a DC in shape of a circuit. edit: you are right...

I'm trying to program a java simulation of some particles in a box. Anyways I want to initialize the particles with random velocities such that on average they're distributed around some velocity. To do this I was thinking about using the nextGaussian() method. Anyways I was initializing...

Let x_1, x_2, ..., x_n be identically distributed independent random variables, taking values in (1, 2). If y = x_1/(x_1 + ... + x_n), then what is the expectation of y?

Hello, Is it possible for this to be... ? Could it be that the whole universe will eventually become so full of super massive black holes, that they all draw in together under their combined gravity, and the universe will eventually collapse into a single point, where another big bang occurs...

Hello Everyone, Im new to this forum and would like to learn more about randomness and probability. I would like to know how I would be able to develop an algorithm (as a function of time) in order for a specific string of characters be known. Are there any hints for me to start with...

Homework Statement X1, X2, X3 are three random variable with uniform distribution at [0 1]. Solve the PDF of Z=X1+X2+X3. Homework Equations The Attempt at a Solution PDF of Z, f_z=\int\intf_x1(z-x2-x3)*f_x2*f_x3 dx2 dx3 I saw the answer at http://eom.springer.de/U/u095240.htm, but I cannot...

Homework Statement Suppose X has an exponential with parameter L and Y=X^(1/a). Find the density function of Y. This is the Weibull distribution Homework Equations The Attempt at a Solution X~exponential (L) => fx(s)= Le^(-Ls) Fx(s)=P(X<s) = 1-e^(-Ls)...

Hi, I'm trying to read into CTRW, but I'm finding the information online a little difficult to take in. From what I've read the process differs from normal random walks in that jumps take place after some waiting time \tau, which can be from 0<\tau<\infty. Would I also be right in saying that...

Homework Statement I was given three plots of solutions for a forced exponential diffeq: y'[t]+1.85 y[t]=0.7t^2 with starter values on y[0] equal to -6, 0,and +7 The three plots eventually merge, how do I give the formula for this parabola? Homework Equations E^(-r t)...

I was given three plots of solutions for a forced exponential diffeq: y'[t]+1.85 y[t]=0.7t^2 with starter values on y[0] equal to -6, 0,and +7 The three plots eventually merge, how do I give the formula for this parabola?

So I want to know if these are true or false, if false why are they A geodesic is a path between two points in spacetime that maximizes the invariant distance ds2. A massive particle's rest mass increases with velocity. If I re a laser beam in the general direction of a black hole...

Howdy guys. Given that X is a random variable how would you prove |X| to be one too? Thanks for any suggestions!

i.e something happening out of nothing or was there no birth at all and all that exists today existed since forever?

The only reliable method of generating random numbers according to a Zipf distribution I have been able to find was here...

Hi, I have a problem (1) where I need to compute the ratio of probabilities of hitting and stopping at a positive vertical barrier x vs hitting and stopping at a negative horizontal barrier y after starting from (0,0). I feel that by symmetry, the answer to this would be the same as...

Hi 1) Suppose that it is known that in a certain large population,10%of is is colourblind. If a random sample of 25 people is drawn from the population, find the probability that exactly 8 of them are colourblind. My Take: is to use the Poisson Probability: f(x)= (e^-\lambda)* \lambda x/x...

Homework Statement Let X and Y be jointly absolutely continuous Random Variables. Suppose X~Exponential(2) and that P(Y>5|X=x)=e-3x. Compute p(Y>5).Homework Equations X~Exponential(2) means that its a exponential distribution integrated from -inf to inf, then sub lambda as 2. The Attempt at...

Homework Statement Let X have mean u and variance s^2. Find the mean and the variance of Y=[(X-u)/s]Homework Equations The Mean is linearThe Attempt at a Solution I thought to just plug in the mean of X anywhere i saw it in Y so mean of Y would be 0 and then for the variance I was kind of...

Homework Statement Let X~Bernoulli(θ) and Y~Geometric(θ), with X and Y independent. Let Z=X+Y. What is the probability function of Z? Homework Equations The Attempt at a Solution I am getting PX(1) = θ PX(0) = 1-θ PX(x) = 0 otherwise pY(y) = θ(1-θ)^y for y >= 0...

Homework Statement Generate Geometric RV with Porbabilty of succcess 0.1 using only rand() Homework Equations rand() geometric rv P=(1-p)^(k-1) * p where p=0.1, k is number of trial in which we get 1st success The Attempt at a Solution rand(n)

I'm trying to contruct a program that will generate a different random number between 1-10. I am not sure how to make it only 1-10. PROGRAM guess USE const IMPLICIT NONE INTEGER::i REAL(kind=dp)::x call random_number(x) WRITE(*,*) 'x=',x END DO END PROGRAM...

Hello all, I am trying to use a random function that my professor gave me:double rnd(int a){return (double)((a * random()) % 1000000000) / 1000000000; }Yes, I did include <stdlib.h>, <stdio.h>, and <math.h>. However, my compiler (Microsoft Visual Studio 2010 C++) does not recognize it as a...

What is the Matlab code for generating 100,000 Raleigh Random Variable with sigma^2=2 using rand command only. Generate histogram and normalize it by dividing 1,00,000 times the bin width

I am a grad student of communication systems but earned a Bsc in physics . I am taking a module presently called Digital communication which require a lot of probability and random processes which I never did while in school. Could anyone give me advice on how I can study for probablity and...

It has been awhile since I took Physics. The other day my daughter asked some questions about force. She told her teacher explained if the object is moving horizontal the push force is 0. I said that can't be right. There has to be a force to overcome friction. This lead me thinking...

Homework Statement 1. Suppose u flip a coin Z = 1 if the coin is heads Z = 3 if the coin is tails W = Z^2 + Z a) what is the probability function of Z? b) what is the probability function of W? 2. Let Z ~ Geometric (theta). Compute P(5<=Z<=9). Homework Equations The Attempt at a Solution...

Homework Statement A clown stands at the side of a swimming pool. In his hand is a bag containing n red balls and n blue balls. At each step he puts his hand into the bag and pulls out a random ball and throws it away. If the ball is red, he makes a step towards the pool and if it is blue...

Well, I thought I understood the difference between (weak) convergence in probability, and almost sure convergence. My prof stated that when dealing with discrete probability spaces, both forms of convergence are the same. That is, not only does A.S. convergence imply weak convergence, as...

http://www.mathworks.co.uk/products/matlab/demos.html?file=/products/demos/shipping/matlab/inverter.html http://www.mathworks.co.uk/products/demos/shipping/matlab/inverter_01_thumbnail.png ^^^ Random matrix, 100x100...

I've read a book named "Cheating Time : Science, Sex and Aging" by Roger Gosden. There he mentions that natural selection occurs as a process of mutations. So suppose we have some individuals of a species that have suddenly got some mutation which gives them better chance of survival in a given...

Hi all, this has been bugging me so maybe you can help me out. In the front window of my house, there is a dent in the glass that looks somewhat similar to this: http://www.flickr.com/photos/guerra/2557095422/" However, there is not hole in the glass. But the shape of the dent is...