1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Variance and Expected Value Problem

  1. Oct 11, 2011 #1
    Give an example of a random variable (i.e. give the range of values it takes and its p.m.f.) with the following properties: EX = 4, VAR(X)=4. Now give an example of a random variable with a different p.m.f. than the first one you gave, but that still has EX = 4, VAR(X)=4.


    So this means then E(X) = E(X^2) - (E(x))^2 right?
    I'm not sure if this is the way I should approach the problem?
     
  2. jcsd
  3. Oct 12, 2011 #2

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Not really. They just happen to equal the same number. What I would do is first find a random variable A with a mean of 0 and variance of 4. Then the variable B=A+4 will have a mean of 4 and a variance of 4.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Variance and Expected Value Problem
  1. Expected value problem (Replies: 8)

  2. Expected value (Replies: 10)

  3. Expected value (Replies: 7)

Loading...