Joint Definition and 297 Threads

If A and B are two events and I want to look at their joint probability P(A.B) do I have to be concerned with the order in with A and B occur? Saurav

fx,y = 6(x-y)dydx, if 0<y<x<1 how do you find E(XY), i know the formula...g(x,y)fxy(x,y)dydx but i don't know what 'g(x,y)' represents and the limits to use??

Joint PDF --> Marginal Pdf's Homework Statement Suppose that the random vector (X, Y ) has the probability density function (pdf) fX,Y (x, y) = k(x − y), if 0 < y < x < 1 0, otherwise. 1. Find the value of k, so that fX,Y (x, y) is a genuine pdf. 2. Find the marginal...

Homework Statement Basically, I am looking to find the reaction forces at the pin joint on the right side of the structure. I just realized it is not labeled on my diagram, but it is the pin on the link opposite of E. Where the 13 degree angle is measured from. Homework Equations I have...

This is a problem given for laboratory analysis, but there are no relevant equations in our textbook to help solving the problem. Could anyone just give me a hint on what equation should be used to solve the problem? the only relevant equation I know is : shear stress = F/A 1. The figure...

I read two articles recently and I am wondering if I have the correct interpretation of them. They deal with joint weak measurement and Hardy's paradox. Is the result of the "Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair" paper indicating...

Suppose that h is the probability density function of a continuous random variable. Let the joint probability density function of X, Y, and Z be f(x,y,z) = h(x)h(y)h(z) , x,y,zER Prove that P(X<Y<Z)=1/6 I don't know how to do this at all. This is suppose to be review since this is a...

Assume that two random variables (X,Y) are uniformly distributed on a circle with radius a. Then the joint probability density function is f(x,y) = \frac{1}{\pi a^2}, x^2 + y^2 <= a^2 f(x,y) = 0, otherwise Find the expected value of X. E(X) = \int^{\infty}_{- \infty}\int^{\infty}_{-...

Let X, Y, and Z have the joint probability density function f(x, y, z) = kx(y^2)z, for x>0, y<1, 0<z<2 find k \int_{0}^{2}\int_{- \infty}^{1}\int_{0}^{\infty}kxy^2z dx dy dz This integral should equal 1. Is my procedure correct so far? I don't manage to solve the integral...

If f(x,y) = 4xy, for 0<x<1, 0<y<1 f(x,y) = 0, elsewhere What's the probability that X<Y? It seems likely that the probability is 0.5, but how can I show it matematically?

Homework Statement A framework of pin jointed members has to be designed to support a plug introduced into the reservoir wall to prevent leakage and further progression of a crack along the wall. The plug is cylindrical, has a diameter of 0.35 m and is supported by a single pin joint. The...

Homework Statement I have a square beam with a screwed joint at each end. I am trying to determine deflection under a uniformly distributed load. Homework Equations - What is a simplified form for the screwed joint? Is it to be assumed fixed at both ends? The Attempt at a...

Could anyone help to give an example where in the same proba space, x and y have each the density function, while the joint density function does not exist? Thanks in advance, Best regards

Hi, I am a quantum physicist who needs a practical help from mathematicians. :smile: The physical problem that I have can be reduced to the following mathematical problem: Assume that we have two correlated variables a and b. Assume that we know all conditional probabilities P(a|b), P(b|a)...

Homework Statement Calculate the knee joint angle based on the XY coordinates of the hip, knee and ankle joint centres. Hip joint(x = 1.0183, y = 0.7959) Knee joint(x = 1.1223, y = 0.5042) Ankle joint(x = 1.0539, y = 0.1081) Homework Equations θjoint = θproximal −θdistal The...

An aluminum wire of length .6 m, cross sectional area of .01 cm^2, density 2.60 g/cm^3, is tied to a steel wire of density 7.8 g/cm^3 and the same cross sectional area. The compound wire is joined to a pulley and then a block of mass 10 kg is tied at the end of the steel wire. Thisi is...

Homework Statement The following table gives the joint probability mass function (p.m.f) of the random variables X and Y. http://img170.imageshack.us/img170/555/tableph9.jpg Find the marginal p.m.f's P_X \left( x \right) and P_Y \left( y \right) 2. The attempt at a solution I think I have...

Homework Statement Let X1, X2, X3,...Xn be independent and indentically distributed with pdf f_X(x)= 4x^3 for 0 < x < 1 First I had to calculate the joint pdf of distribution of X1, X2, X3..Xn which I did I got 4(X1*X2*X3*...*Xn)^3 Which I'm hoping is correct. a) determine the...

Homework Statement Consider two components and three types of shocks. A type 1 shock causes component 1 to fail, a type 2 shock causes component 2 to fail, and a type 3 shock causes both components 1 and 2 to fail. The times until shocks 1, 2, and 3 occur are independent exponential random...

I have a general question about solving these types of problems. I had two different problems for calculating the tensions and compressions of a pin-jointed truss. both problems were of a trapezoidal shape with 5 pins in total. in one problem, a weight was applied to the center truss on...

Homework Statement Consider a rod length L and mass m which is pivoted at one end. An object with mass m attached to the free end of the rod. g=9.8 m/s^2. Note: Contrary to the diagram shown, consider the mass at the end of the rod to be a point particle. Basically it looks like a rod...

Random variables X and Y have the joint PMF PX,Y(x,y) = c|x+y| x=-2,0,2; y=-1,0,1. 0 otherwise 1) what is the value of constant c? 2)what is P[Y<X]? 3)What is P[Y>X]? 4)what is P[Y=X]? 5)what is P[X<1]?

Suppose one knows a probability density p(x) over a space X (where x\in X) and a conditional probability density p(y|x) over a space Y (where y\in Y). This implies the integral \int{p(x)dx} is well defined as well as \int{p(y|x)dy}. Defining a joint probability density p(x,y)\ =\ p(y|x)p(x)...

This is the program I'm thinking about doing. What do does everyone here think? anyone do anything similar? any idea what kind of job opportunities would be available to me? thanks! Dylan

Is it better to do a joint honours degree in physics and math or a honours degree in math and a minor in physics? Joint Honours Course Schedule: http://www.math.mcmaster.ca/prospective/Prospective%20Students/mathphysics.pdf Applied Mathematics Specialization Course Schedule...

Can anyone tell me how to find the joint PDF of two random variables? I can't seem to find an explanation anywhere. I'm trying to solve a problem but I'm not sure where to go with it: Y is an exponential random variable with parameter \lambda=4. X is also an exponential random variable and...

Homework Statement Let's say there are two machines, X and Y. X is connected to Y. * If X is turned on, Y turns on 50% of the time. * If Y turns on (through X being turned on) then it breaks 25% of the time. * Y won't break spontaneously and it can only be turned on through X. What...

Which of the two would you recommend? I'm thinking that a joint degree in Math and Physics would be better for graduate studies, but the courses for a simple physics degree sound "more fun": http://www.physics.mcgill.ca/ugrads/math.html http://www.physics.mcgill.ca/ugrads/honours.html...

Homework Statement please help i have just been introduced to shear stress and can do the basics i have just got a problem with this homework question and i am after some pointers as how to tackle it here's the question TWO STRIPS OF STEEL,100*2.5MM,ARE SPOT WELDED TOGETHER TO FORM A LAP...

http://folk.ntnu.no/bronner/temp/temp1178774511.57813.png Or am I missing somthing obvious?

Hi, I would like some help with this problem If X1 and X2 are two discrete random variables with joint probability distribution given by the following bivariate table.(table attached) 1-Find the conditional probability distribution of X2 given X1. thank you

Homework Statement See Attachment Homework Equations The Attempt at a Solution Im not really sure how to get started. I understand the method of Joints, and all the solved examples I can follow. I started by analyzing the support reactions, and I am stuck already. There is...

Homework Statement Can anybody help me calculate the approximate force/ stress on a hip joint during walking and/or running Any help is greatly appreciated. Homework Equations The Attempt at a Solution

X1, X2, X3 are independent gaussian random variables. Y1 = X1+X2+X3 Y2 = X1-X2 Y3 = X2-X3 are given. What is the joint pdf of Y1,Y2 and Y3 ?

I'm having a problem evaluating a distribution- Suppose X and Y are Chi-square random variables, and a is some constant greater than 0. X and Y are independent, but not identically distributed (they have different DOFs). I want to find P(X>a,X-Y>0). So I use Bayes' theorem to write...

Let X be a random variable with mean \mu and standard deviation 1. Let's add a twist. Suppose \mu is randomly distributed about 0 with standard deviation 1. At each iteration, we select a new \mu according to its distributuion. This mean is then used in the distribution for X. Then we pick...

I am after a way to cook a joint of beef so as i can use it for my sarnies, when i do it it ends up dry and cardboardy after a few days, is there a marinade that will help preserve the beefiness and texture, that deli stuff is not bad but it lacks the taste of home cooked joint.

Hi, I have a situation where there are N random events. These events can be from either one of two sources, one with a binomial distribution, the other with a Poisson distribution. The events do not provide any evidence of their origin, either distribution could be responsible for creating...

rivet joint designs... Hi, Im in desperate need of a good link where i can read up about rivet joint designs with gusset plates etc. (specifically i need to know suitbale designs for a bridge structure made from aluminium angle and strip) however general information would be just as good...

Given this joint PDF of X and Y: X\Y 1 2 0 0.1 0.3 1 0.05 0.1 2 0.2 0.25 So: P(X = 1| X+Y=2) = 1/2? P(X <= 1 and Y <= 2) = 1/3?

Hi I am trying to calculate a particular problem from a given bayesian network. The network consists of nodes G1,G2,G3,G4,Pr1 G1 leads to G2, G2 leads to G4 and G3 also leads to G4 but it has no parents, and G4 leads to Pr1. The probability tables for the nodes are: P(G1) = 0.02...

Ok Whats the general way to solve problems such as these? -Let X and Y have the joint pdf f_X,Y(x,y) = 2e^-(x+y) , 0 < x < y, 0 < y Find P(Y < 3X). -Find P(X < 2Y) if f_X,Y(x,y) = x + y for X and Y defined over the unit interval (meaning from 0 to 1). I know you have to set up the double...

Lets say you have X and Y, where the joint density function for X and Y is uniform over the region defined by 0<=x<=y<=L, where L is some positive constant. The question asks for the expected value of the squares of X and Y. I am having trouble visualizing what such a distribution would...

A copper rod and an aluminum rod of the same length and cross-sectional area are attached end to end. The copper end is placed in a furnace which is maintained at a constant temperature of 279oC. The aluminum end is placed in an ice bath held at constant temperature of 0.0oC. Calculate the...

so X and Y have joing pdf f X Y(x, y) = 1/2 for 0 < y < x < 2, and 0 otherwise. find P(0< Y < 2/5 | X = 3/4) first, I don't understand how to read the function. So the function is equal to 1/2 when 0 < y < x < 2. And it is equal 0 otherwise. So I need to find Probabilty Y is between 0...

If the values of the joint probability density of Y1 and Y2 are as shown: 0 1 2 total 0 1/12 1/6 1/24 35/120 1 1/4 1/4 1/40 63/120 2 1/8 1/20 ... 21/120 3 1/120 ... ... 1/20 ttl 56/120 56/120 8/120 1 whew ;-) ok Find a) P (Y1=0) b) P(Y2=1 | Y1=1) c P(Y2=1) e Check if Y1...

If the values of the joint probability density of Y1 and Y2 are as shown: 0 1 2 total 0 1/12 1/6 1/24 35/120 1 1/4 1/4 1/40 63/120 2 1/8 1/20 ... 21/120 3 1/120 ... ...