Joint Definition and 297 Threads

Does anyone know how to solve the question below? I have no idea to do it with some missing angle inside the triangle. [PLAIN]http://img267.imageshack.us/img267/374/truss.jpg Shot at 2012-07-01

Suppose that (X,Y) is uniformly distributed over the regiondefined by 0≤ y ≤ 1-x2 and -1≤ x ≤ 1. a) find the marginal densities of X and Y Attempted solution: So first I have to find the joint density function which ends up being fxy(x,y) = 3/4 and then from that I would solve...

I am building a device out of 1/4" brass tubing. I need to join lengths in such a way as to allow the tubes to flex up to 135 degrees from straight. I haven't been able to figure out how to get that much rotation from a ball joint without the joint falling apart.See attached diagram below for...

it seems that i can't understand the boundaries... the joint density function: f(u,v)= a , u^2 <= v <= 1 0 , else find a i just don't know how to start. any help ? thx

Hi all i have problem with my h.w , i think the question is related more to math than to probability, but I'm sure someone here will find how to help me so i attached my solution with the question, i think i have difficulty to find the right boundaries of the marginal density function of...

Is it possible to simulate a bushing joint between to parts that would also conduct heat from one part to another?

The following question appeared on a practice exam: For f(x,y) = 24xy if 0<x+y<1 , 0<x,y 0 elsewhere find Cov(X,Y) I used Cov(X,Y) = E(XY) - E(X)E(Y) to calculate covariance, with E(XY) = \int^{1}_{0}\int^{1-y}_{0}24x^{2}y^{2}dxdy but for some reason I didn't get the...

Homework Statement Let U,Y be independent random variables. Here U is uniformly distributed on (0,1) Where as Y~0.25\delta_{0} + 0.75\delta_{1}. Let X = UY. Find the Cdf and compute P(0≤X≤2/3) The Attempt at a Solution Normally a question like this is fairly straightforward but I'm having...

Homework Statement Let X1 and X2 be random variables having a joint pdf, fX1X2(x1,x2). Suppose that Y1=X1X2, and Y2=X1X2 Use the transformation result to derive an expression for the joint pdf of Y1 and Y[SUB]2 in terms of that for X1 and X2 Homework Equations The single random...

http://dl.dropbox.com/u/33103477/Joint.png This is my interpretation of the limits of integration can you tell me if this is correct and also how do you calculate these limit's. Cause I'm not completely sure how they're calculated. \int_{0}^{1}\int_{1-y}^{1} ce^x e^y dx dy

hello friends, i am currently working on a project in which a steel rope is used to carry an object in a loop just like a chair lift. what i want to ask is what method can i adopt to make a joint of the rope that can pass through or over the pulleys and not de-track too. The rope diameter is 8...

Homework Statement Find λ given that the joint PDF of random variables X, Y, is given by: f(x,y)=\lambda x y^{2} where 0\leq x\leq y\leq 1 and 0 otherwise I have two questions: 1) How do I graph this? I'm not sure how to approach the inequality and graphing. What does this inequality...

How would you work out E[XY] where X,Y are dependant variables in a Joint Distribution. I know there is a relationship with the conditional distributions but I can't understand the logic behind it, hence am hoping someone here can give me directions to work out this expectation.(I don't just...

I am making a robot that entails a moveable base and a basic moving arm. I have made a force diagram using a 50kg, 110lb weight 9the maximum intended load. Doing the math (some of it I rounded) I would need at least 540 N of force to raise the weight. How could I design a shoulder joint in such...

Joint Distribution (Means,Medians...) PLEASE HELP! Hi, I'm wondering if somebody could help me understand this... If you have a joint distribution with Hourly Wage (Y) Years of Education (X) 9 15 30 10 0.07 0.02 0.01 14...

I'm trying to make an elbow joint for a robotic arm that is actuated with a stepper motor and two gears. Here's a quick sketch of what I'm trying to do: http://imgur.com/mBlg7 The two bottom plates will be attached to the 'bicep' and the two upper plates will be attached to the 'forearm.'...

Hi group, I'm a theoretical ecologist with fairly adequate training in applied math (ODE, linear algebra, applied probability, some PDEs). In my current work, I've encountered the use of adiabatic approximation to a joint probability distribution of two ever-fluctuating spatial variables. A...

Homework Statement I have access to P(x|A) and P(y|A), P(x), P(y) and P(A), in addition to the knowledge that x and y are independent variables. I am interested in finding P(A|x,y). The Attempt at a Solution I think that P(A|x,y) = P(x,y|A) * P(A) / P(x,y) = P(x,y|A) * P(A) /...

Hi guys, I'm really stuck on the following questions, not sure as to how to approach it: Let X and Y be random variables for which the joint pdf is as follows: f(x,y) = 2(x+y) for 0 <= x <= y <= 1 and 0 otherwise. Find the pdf of Z = X + Y And also: Suppose that X is a random variable for...

Homework Statement i'd try to write the code for this question :(Discrete random variable X & Y have a joint distribution : Fx,y(x,y)=0.1u(x+4)u(y-1)+0.1u(x+3)u(y+5)+0.17u(x+1)u(y-3)+0.05u(x)u(y-1)+0.18u(x-2)u(y+2)+0.23u(x-3)u(y-4)+0.12u(x-4)u(y+3) Homework Equations I try this code in...

I'm posting this here, as i feel it's more probability-related than image processing. I'm reading this lecture pdf. At end of page 1 , beginning of page 2 it says: Is this a bit vague, or am i missing something? Since we are calculating frequency of the value a in the pixels of image A, when...

I hope I wrote that correctly but I'm trying to find the joint. I heard it was impossible from someone. X = A/R A~BIN(n1, p1) R~BIN(n2, p2) I know I shouldn't be using the Jacobian method for Discrete distributions but I have to do it anyway. Anyone know?

Hi, I've no idea where to go with the question below: Joint moment generating function of X and Y - MXY(s,t) = 1/(1-2s-3t+6st) for s<1/2, t<1/3. Find P(min(X,Y) > 0.95) and P(max(X,Y) > 0.8)

This is inspired by Kardar's Statistical Physics of Particles, page 45, and uses similar notation. Homework Statement Find the characteristic function, \widetilde{p}(\overrightarrow{k}) for the joint gaussian distribution: p(\overrightarrow{x})=\frac{1}{\sqrt{(2\pi)^{N}det...

Homework Statement I have: f_A=\lambda e^{-\lambda a} f_B=\mu e^{-\mu b} (A and B are independent) I need to find the density of C=\min(A,B) 2. The attempt at a solution f_C(c)=f_A(c)+f_B(c)-f_A(c)F_B(c)-F_B(c)f_A(c) =\lambda e^{-\lambda c}+\mu e^{-\mu c}-\lambda e^{-\lambda c}(1-e^{-\mu...

I have: $f_A=\lambda e^{-\lambda a}$ $f_B=\mu e^{-\mu b}$ I need to find the density for $C=\min(A,B)$ ($A$ and $B$ are independent). Is this correct or utterly wrong? $f_C(c)=f_A(c)+f_B(c)-f_A(c)F_B(c)-F_A(c)f_B(c)$ $=\lambda e^{-\lambda c}+\mu e^{-\mu c}-\lambda e^{-\lambda...

Simple joint distributions such as X+Y are usually worked out in textbooks, but how would we approach a general case. For example, let X any Y be independent variables each defined on the interval [0,infinity], and having densities f(x) and f(y) respectively. How do we find, for example, the...

Homework Statement Hello. I have a problem with setting up the lagrangian for a system here. The problem is stated at page 8 problem 2.3 with a diagram at the following -->link<--- 2. The attempt at a solution I used two generalized coordinates corresponding to the angle between...

Homework Statement Determine force of each member using joint method Homework Equations T = F x D The Attempt at a Solution Answers are: Fab 2465 T Fbd 1200 T Fbc 1375 C Fdc 750 C Fde 860 T (This one is what I tried) Fce 649 C Fac 1922 C Thanks.

I need some help. Is there a good way to do this type of question? Homework Statement Let X and Y be independent random Variables with exponential densities fX(x) = Ωe-Ωx, if X≥0 0, otherwise fY(y) = βe-βy, if y≥0 0, otherwise...

Right now I am a junior working towards an Engineering Physics degree and an EE minor. In addition to the physics, I've been/plan on taking a few EE and MSE classes that I have thought would be useful and interesting in the kind of work I could see myself doing. I looked over the MSE/EE joint...

Hi, This is my first post in one of these forum; I hope someone can help me with this --thanks in advance for reading! I'm trying to find the joint probability distribution of two non-independent variables given only their marginal distributions. In fact, I'm interested in the joint...

I solved majority of the question I just need to find the last joint density. Found the equations at part 3. Homework Statement Show P(X-Y=z ,Y=y) = P(X) = P(|Y|) I showed P(X) = P(|Y|) Homework EquationsThe Attempt at a Solution P(X=x,Y=y) = \frac{2*(2x-y)}{\sqrt{2πT^3σ^6}} *...

Homework Statement Suppose that X=time to failure for a component has an exponential distribution with lambda =.25. Suppose that 9 of the components are selected and their failure times noted. Compute the probability that 3 of the components fail between times 1 and 2, and 4 of the components...

X~Pois(λ)=> px(k)=e-λλk/k! Y~Pois(μ)=> py(k)=e-μμk/k! Find pX,X+Y(k,n)=P(X=k, X+Y=n) ...I know the pmf for X+Y ~ Pois(λ+μ) As I understand the joint pmf for two independent random variables would be the product of the two individual pmfs. However as X+Y is dependent on X I got really...

Homework Statement X~Pois(λ)=> px(k)=e-λλk/k! Y~Pois(μ)=> py(k)=e-μμk/k! Find pX,X+Y(k,n)=P(X=k, X+Y=n) Homework Equations ...I know the pmf for X+Y ~ Pois(λ+μ) The Attempt at a Solution As I understand the joint pmf for two independent random variables would be the product of the two...

Homework Statement I have been given a joint PDF for X and Y, with ranges Y>X≥0. I need to find the E(x) and E(y). Homework Equations I know E(x) = ∫(x)*(f(x,y) dx and E(y) = ∫(y)*(f(x,y)) dyThe Attempt at a Solution For ∫x*f(x,y) dx, i used the limits = x to ∞ For ∫y*f(x,y) dy, i used the...

Yes - I know this is a physics forum, but technically chemistry is a result of physics, and the chemical forums are relatively unpopulated, so I thought I'd ask you all about this as well (if it helps, replace every instance of the word 'chemistry' with 'physics')... I graduated with a B.S...

Hi! I would be really happy to receive some help. I have tried using Jacobians and so on, but I am stuck. I'll start with the univariate case. Let X ~ N(μ,σ) and Y = exp(X)/(1+exp(X)). What is the joint f(x,y)? According to intuition fy|x = 1, but since we are dealing with continuous...

Hi everyone. This is my first post on the forums. I wanted to ask your expertise on a project I'm working on. I'm trying to design a setup where I rotate a ∏ shaped frame that has a 1kg load on the horizontal bar. The space between the frame should stay empty. The length of the side rods...

Hi, I have the following question : How do we estimate the joint probability Pr(X_1, ... X_n) when n \rightarrow \infty ? Thanks a lot.

Have an example: 123455 111555 the sample space is 0..9 row 1 can pick 6 numbers out of which 2 are repeated row 2 can pick 6 numbers out of which 3 by 3 are repeated I want to know what is the real probability that row 1 will match with 2 distinct numbers numbers row 2, and a repeated number...

Homework Statement Hi, if you could offer help to any of these questions, it would be great, i was unable to attend my lectures this week and I had no idea how to do these. The joint pmf of x and y is p x,y = c(x^2 + y^2) x,y = 1,2,3 Find: a. c and the marginal pmfs of x and y b. e(x)...

Hi all, I am having trouble with the concept of joint pdf's. For example - a set Z1,Z2,...ZN are each gaussian rv. Let Z1~N(0,1), let X be +1 or -1 each with probability 0.5. Z2=Z1X1, so Z2 is ~N(0,1). (I assume this to be As Z2 is just Z1 multiplied by a simple factor, an instance...

X and Y are 2 independent gaussian random variables with parameter a. Z = XY / (X-Y) W = XY / |X-Y| I am to find the joint distribution function of z and w. I know how to find pdf of Z but how could I use it to find the joint distribution function of z and w?

I'm having a trouble doing this kind of problems :S Lets try this for example: The joint p.d.f of the continuous random variable X and Y is: f(x,y)= (2y+x)/8 for 0<x<2 ; 1<y<2 now we're asked to find a probability, say P(X+Y<2) I know i have to double integrate but how do I choose my...

Homework Statement Of 25 light bulbs, 5 are defective. 8 bulbs are chosen from the 25. What is the probability that 2 or fewer of the 8 selected light bulbs are defective? Homework Equations The Attempt at a Solution It's been awhile since I've done questions like this one. I was...

A bag contains three green beads, two red beads and a blue bead. You select two beads at random. Let G denote the number of green beads and R the number of red beads you select. (a) Write the joint probability distribution of (G,R) in a table. Show that Cov(G;R) < 0. I can do P(G=g)...

My answer is not really close to the answers provided. They break up the joint distribution into x less than y and y less/equal to x. They have a 1 in their cases. I don't. http://i111.photobucket.com/albums/n149/camarolt4z28/Untitled-1.png?t=1302832281...

Would just like a hand with this question If X and Y are independent standard Gaussian random variables (that is, independent N(0, 1) 's ) do the following: (a) Write down the joint probability density function fXX,Y (x, y) of X and Y . I know what the gaussian density function looks...