I need quickly help Probability and Statistics questions

Discussion in 'Math' started by couldi, May 8, 2012.

  1. couldi

    Thread Starter New Member

    Feb 28, 2012
    ----The random variables X and Y are N(0,2) (Normal or Gaussian distributed) and independent. Find the PDF and CDF of Z = 2X + 3Y.

    -------Two fair dice are rolled. Find the joint probability mass function of X and Y when X is the largest value obtained on any die and Y is the sum of the values.

    ------Given the joint PMF of X and Y as
    {1/4 (x,y)=(1,1) }
    {1/4 (x,y)=(-1,1) }
    {1/2 (x,y)=(0,0) }
    { 0 otherwise }
    (a) Find E[X], E[Y], and E[XY],
    (b) Show that X and Y are uncorrelated,
    (c) Determine if X and Y are independent or not.

    -------The joint density function of X and Y is
    { x+y 0<x<1,0<y<1
    0 otherwise }

    a) Are X and Y independent?
    b) Find the density function of X?
    c) Find P(X+Y < 1)=?

    ------Suppose the joint density function of X and Y is given by

    {((e^-x/y) * (e^-y))/y 0<x<oo , 0<y<oo
    0 otherwise }

    a) Find the conditional density of x, given that Y=y.
    b) Find P(X > 1 | Y = y).


    Last edited: May 8, 2012
  2. Wendy


    Mar 24, 2008
    Please use local hosting for pictures and files. Your like isn't working correctly for me, even though the image at the home site is OK.

    How to attach a picture

    To attach a document or picture to a post

    Click "Go Advanced" at the bottom of your post,

    One of several options will pop up,

    Click "Manage Attachments" much further at the bottom of your post,

    To upload a file from your computer click "Browse", then select the file.

    Schematics should be .gif or .png format, pictures should be .jpg. .jpg formats will fuzz out schematics, and should not be used for that purpose.


    If you want to display this file there is an old thread I made,

    How to Display Attachments Full Size
  3. WBahn


    Mar 31, 2012
    What help do you need? What questions do you have? Just posting the problems that you are expected to solve doesn't accomplish much.

    Take the problems one at a time. Describe what you have done or how you think the problem solution should be approached, and try to ask specific questions that will help you take the next step.

    If nothing else, describe what you believe you know about the problem and whatever initial steps you have taken and others will point out problems with your approach, things you have not taken into account, or ask questions that will guide you toward taking what you have already done and making the next logical step.
  4. francescot

    New Member

    May 10, 2012
    Hi, i need these solutions immediately it makes me happy if you send me the solutions of these 5 questions. Thank you for your help. Have a nice day.
  5. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    I suggest you review this link, although it may be too late given your last post. It describes the best way to ask for help. This looks like homework, so I got these guidelines from the "Homework" section: http://forum.allaboutcircuits.com/showthread.php?t=3002

    I have included a short excerpt from this sticky post (emphasis added).