Random Definition and 1000 Threads

Hi In http://sl-proj-bi-specification.web.cern.ch/sl-proj-bi-specification/Activities/Glossary/techglos.pdf it says that: ... if the sources of uncertainties are numerous, the Gaussian distribution is generally a good approximation. I don't quite understand why. The Central Limit Theorem (CLT)...

The transformation of a random variable is well documented and there are numerous examples on the web. Most examples present univariate variable transformation utilising inverse of the transformation function. The method works whenever the transformation function is one-to-one. Let's say...

Comment made by an 11 year old accompanied by her grandmother after she entered the Subway I was eating at, somewhere in The Bronx, NY: "Why would I want to learn math? Just so I can work at a cash register?" I wanted to cry...:frown: Where would she get that idea from?

I am trying to linearize a function, f(x), where x is a normally distributed N(0,1) random variable. How can I perform a taylor series expansion around a deterministic value x0? Thanks.

What is the motivation behind random variables in probability theory? The definition is easy to understand. Given a probability space (Ω, μ), a random variable on that space is an integrable function X:Ω→R. So essentially, it allows you to work in the concrete representation R instead of the...

The only requirement is that the pure random numbers generated have to be purely random to its creator, not for some other inferior species. (To keep Evo happy, a super being is someone who is omniscient and omnipotent.)

Homework Statement Continuous random variable X has probability density function defined as f(x)= 1/4 , -1<x<3 =0 , otherwise Continuous random variable Y is defined by Y=X^2 Find G(y), the cummulative distribution function of Y Homework Equations The Attempt at a...

Ok I am not sure if I should put this question in the homework category of here but it’s a problem from schaums outline and I know the solution to it but I don’t understand the solution 100% so maybe someone can explain this to me. Let X and Y be defined by: \begin{array}{l} X = \cos \theta...

If X is uniformly distributed over [0,a), and Y is independent, then X + Y (mod a) is uniformly distributed over [0,a), independent of the distribution of Y. Can anyone point me to a statistics text that shows this? Thanks,

1 Calculate the expected value of variable x (or E(x)) (number of trials * probability of success) 2 Calculate the variance (expected value * probability of a failure) Take everything to the right of the decimal in the variance off. Then the range of future values is E(x) plus/minus the variance.

Hi I'm making a program that generates a different arrangement of letters in C. For example, the word ALTEC will be rearranged randomly by the program. the output would be "LETAC" or "CEALT" etc. The program should use all the given letters and not repeat the letters. Here's a code...

Please help - I am helping a student who is trying to translate Ong-Schnorr to C++ or VB.net language. My major was electronics so I am not sure how to interpret inverse random integer k. Any one ? or suggest me a reference to read on - much thanks, newbie Ong-Schnorr-Shamir (from Briuce's...

Hi, I'm modeling receptors moving along a cell surface that interact with proteins inside of a cell. I figured it would be easier to model the receptors in spherical coordinates, however I'm unsure of how to model a random walk. In cartesian coordinates, I basically model a step as: x = x +...

Homework Statement A random variable X takes values 1,2,...,n with equal probabilities. Determine the expectation, R for X and show that the variance, Q^2 is given by 12Q^2=n^2-1. Hence, find P(|X-R|>Q) in the case n=100 Homework Equations The Attempt at a Solution I can show...

Given two random variables x and y, and a constant c What conditions are needed to make: Prob( w x + y < c ) \approx Prob( w x < c ), \text{ for } w \rightarrow \infty Can anyone help? I think E(x) < \infty and E(y) < \infty might do. Is this right? tks!

Hello, I am trying to find a clean solution for this (i.e. straightforward and academically acceptable). I appreciate if someone can help me. 1- I need to select between selections 1 to n (in my case 1-8 ). However each preceding item should have higher probability than the next one. For...

Just to help define what random is Dictionary.com states that it is: "–adjective 1. proceeding, made, or occurring without definite aim, reason, or pattern: the random selection of numbers." But does random truly exist? For example the roll of dice is usually referred to as random, but...

Homework Statement Say, it is known that E_X[f(X)] = E_X[g(X)] = a where f(X) and g(X) are two functions of the same random variable X. What is the relationship between f(X) and g(X)? Homework Equations The Attempt at a Solution My answer is f(X) = g(X) + h(X) where E_X[h(X)] =...

Homework Statement Let U = 0.X1X2X3... be a random number in (0,1]. 1) Find the distribution of every decimal digit Xi, i = 0,1,2... 2) Show that they are independent of each other The Attempt at a Solution I could use a hint for N°2. I have an idea, but I think it's wrong...

Homework Statement Hello, have a stats question I am hoping you guys can help with. The expectation of a function g of a random variable X is: E[g(X)] = \int^{\infty}_{-\infty} g(x)fx(x)dx where fx is the pdf of X. For example, the particular expectation I am considering right now...

Hi, I'm trying to get it so that when the program initiates, if the random number is greater than 3, I turn left. here is what I have in summary; int rt=3; Random ra = new Random(); for (int c = 6; c <12; ++c); { } if(rt<ra) {...

This is a problem from my A levels Stats2 book. I understood the problem but one of my answers doesn't seem to be correct according to the book so I thought I better be sure! Homework Statement A piece of laminated plywood consists of 3 pieces of wood of type A and 2 pieces of type B. The...

Hello! I've been trying to create an algorithm which picks a number randomly from array. P.S i have an array like A={1,4,-1,3,-7,2,-14} and I want to pick a number randomly from array. Any idea? Thank you.

If 2 random variables X, and Y have the same distribution, does that mean that for another random variables Z, X + Z and Y + Z also have the same distribution? From looking at the convolution formula, the answer should be yes, because the convolution of random variables depends only on the...

Hello all, I have the following question: Assume (\Omega, \mathcal{F},P) = ([0,1],\mathcal{B}([0,1]),\lambda), where \lambda is Lebesgue mesure, so is X(\omega) = \frac{1}{\omega} a random variable defined on this probability space? If yes, then can I say that X is bounded a.s. because the...

Hi I am currently reading: http://www.cs.cornell.edu/~asaxena/learningdepth/saxena_ijcv07_learningdepth.pdf which deals with reconstructing depth from a single still image. A gaussian multiscale markov random field is trained in a supervised context where the model is shown below...

Hi all, I have a question of computing the expectation of random sums. E(sim_{k=1}^N X_k) = E(N)E(X) if N and X_1, X_2,...are independent and X_k's are iid. Here both N and X_k's are r.vs. But the condition of N and X_1, X_2,...being independent is not true in many cases. How will...

Dear Friends, I want to find an upper and lower bound for the expected value of the minimum of independent binomial random variables. What paper/book do you suggest for this problem? In other words, I need to find bounds for E(min(X1,X2,...,Xn)), where Xi 's are independent random variables...

Homework Statement A car moving at constant acceleration covers the distance between two points 58m apart in 6.2 seconds. its speed as it passes the second point is 54 km/hr. what is the speed at the first point? at what prior distance from the first point was the car at rest?Homework Equations...

I am working on correcting an exam so that I may study for my probability final. Unfortunately, I don't have the correct answers, so I was hoping that someone here might be able to check my thought process. 1) Pick three numbers without replacement from the set {1,2,3,3,4,4,4}. Let T be the...

Re www.physicsforums.com/showthread.php?t=403487 Actually, there is a move back to writing multiplication left to right. And while it is not wrong that this purely a matter of convention and symmetric within a narrow context, in a wider context, this notational choice acquires very real...

There are no Bayesian Networks for continuous random variables, as far as I know. And the Netica Bayesian Network software discretize continuous random variables to build bayesian models. Are there any reasons for this? Has anyone proposed continuous random variable bayesian networks?

Homework Statement I'm trying to revise for a probability exam in a few weeks and still getting really confused :( so I'd be really grateful for a push in the right direction: Consider a random walker on f0; 1; 2g who moves as follows: - if at 0, probability 1/2 of staying at 0 and 1/2...

Hello, I have read the probability chapter in Feynman's lectures on physics. And got fascinated by the random walk. There is a statement, that in a game where either a vertical distance of +1 or -1 can be walked each move, the expected value of the absolute distance (lets call it <D>) from...

Homework Statement Problem 1 – Normal Random Variables B) Y ~ N(300, 100). Pr (300 < Y < 320) = 0.4772 D) H ~ N(4000, 25). R = f(H) = 0.5H – 60. E(R) = 1940; Var(R) = 156.25I have a problem solving these problems above...I missed the class when we covered this subject and now I am lost...

Homework Statement Given the joint density, f(x,y), derive the probability density function for Z = X + Y and V = Y - X. Homework Equations f(x,y) = 2 for 0 < x < y < 1 f(x,y) = 0 otherwise. The Attempt at a Solution For Z = X + Y, I can derive the fact that, f_Z(z) =...

I am having a lot of trouble conceptually understanding the idea of a random effect in ANOVA testing - more specifically identifying whether a factor is random or fixed Thanks, Thrillhouse86

Homework Statement Given 2 independent uniform random variables X,Y = U [0,1], consider the random variables Z = g (X,Y) for g = (x,y) = sqrt (-2ln(x) . cos(2piy). Since finding the distribution of g(X,Y) analytically is quite tough, I need to generate MATLAB program for 1 - 10,000...

Hi looking for some help on the below I'm a little bit stuck. The effect of an earthquake on an elevated water tank is to be investigated. The water tank has mass m=2x10^6 kg and natural frequency wn=10.6 rad/s and a damping coefficient of 12% critical damping. Ground acceleration can be...

Homework Statement Let X be a posative random variable with probability density function f(x). Define the random variable Y by Y = X^2. What is the probability density function of Y? Also, find the density function of the random variable W = V^2 if V is a number chosen at random from the...

Z = X + Y Where X and Y are continuous random variables defined on [0,1] with a continuous uniform distribution. I know we define the density of Z, fz as the convolution of fx and fy but I have no idea why to evaluate the convolution integral, we consider the intervals [0,z] and [1,z-1]...

Homework Statement X and Y two independent random variables with distribution U(0, 1/2). Find the density of (X + Y)2|X - Y > 0 The Attempt at a Solution I was hoping this would be simpler, but somehow I always end up with nothing. The only thing I can work out just fine is that P(X...

Homework Statement The number of hours that it takes to process a certain type of job is a random variable with mean and standard deviation 2. AAssuming that processing times are independent, approximate the probability that atleast 50 jobs can be sequentially processed within 240 hours...

Homework Statement The RV X has parameter p>0 and distribution: fX(x) = pxe-px for x \geq 0 and is 0 otherwise (The subscript X is a capital letter, as is the X mentioned below in the e4X) If we are to consider the RV D= e4X, determine the range and distribution fD(d) Homework...

Homework Statement X, Y, Z random variables, independent of each other, with uniform distribution in (0,1). C = XY and R = Z2. Without using the joint probability function, find P(C>R). The Attempt at a Solution So far: P(C > R) = P(C - R > 0) = P(XY - Z2 > 0) = P(g(X,Y,Z) > 0)...

Hi All, i got a short question concerning the ev of a monotone decreasing function. when i got a nonnegative random variable t, then its ev (with a continuous density h(.)) is given by E(t)=[int](1-F(t))dt Then if v is a nonpositive random variable, is its ev given by...

I want to use the random number generator in mathematica to give me numbers in the range of 0 to 1, but only to two decimal places. Can anyone help? Thanks.

A bit off the wall, but anyone who plays with random number generators quickly learns that it is impossible to make one that is truly random, using software alone. Has anyone ever considered whether people can actually generate random numbers? How does the mind produce a number "randomly"? Do we...

suppose we have random variable defined a function of another random variable such that Y = \mathbb{E}(X) it seem then Y is a constant. then \mathbb{E}(Y) = \mathbb{E}(X) does this even make sense ?

I need help in partioning bits of random number in matlab! Hey guys, I really need your help here...What i wanted to do actually is to partition the bits into 4 smaller group.. If anyone of you can give me a basic coding of it or maybe u can check if there anything wrong wit my coding...