Joint Definition and 327 Threads

  1. H

    Joint PMF: Value of c, P[Y<X], P[Y>X], P[Y=X], P[X<1]

    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]?
  2. W

    Minimum conditions for defining joint PDF

    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)...
  3. D

    Joint Honours Geophysics/Physics

    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
  4. M

    Explore Joint Honours & Math/Physics Programs: Job Opportunities

    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...
  5. E

    Finding Joint PDF of Two Exponential Random Variables

    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...
  6. J

    Simple joint probability distribution

    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...
  7. P

    Physics or Joint Math/Physics Honours?

    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...
  8. S

    Finding Minimum Number of Spot-Welds for Steel Lap Joint

    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...
  9. Z

    Is the Proof of Joint CDF at NTNU Correct?

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

    Finding Conditional Probability Distribution for Discrete Random Variables

    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
  11. S

    Getting Started: Solving Joint Problems in Structural Mechanics

    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...
  12. M

    Calculating Hip Joint Force/Stress During Walking/Running

    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
  13. K

    Probability : joint density function of 3 Normal Distributions

    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 ?
  14. O

    Joint and conditional distributions

    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...
  15. G

    Joint Distribution of Changing Mean

    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...
  16. wolram

    Preserving the Flavor and Texture of Home-Cooked Beef Joints: Tips and Tricks

    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.
  17. Q

    How do I calculate the joint distribution for N events?

    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...
  18. C

    Rivet Joint Design with Gusset Plates - Aluminium Bridge Structure

    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...
  19. S

    Find the Probability of Joint PDF X and Y with Easy Calculation

    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?
  20. edward

    News Joint Chiefs finally speak out on something

    Earlier in the week the Washington Post published a cartoon by Tom Toles. All six of the joint Chiefs signed a letter that was sent to the post admonishing them for publishing the cartoon. Where were the Joint Chiefs when the armored Humvees or the lack thereof, and the inadequate body...
  21. C

    Bayes Networks - calculations in terms of joint distribution

    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...
  22. A

    Statistics/Probability: Joint Densities

    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...
  23. M

    How to visualize joint uniform distribution

    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...
  24. J

    Calculating Temperature at Copper-Aluminum Joint

    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...
  25. S

    How to Find c for Given Joint PDF?

    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...
  26. L

    How Does Joint Probability Density Determine Dependence Between Variables?

    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...
  27. L

    How to Analyze Joint Probability Density of Y1 and Y2?

    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 ... ...
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