Results 1 to 2 of 2

Math Help - prob

  1. #1
    Newbie
    Joined
    Nov 2009
    Posts
    4

    prob

    E3. Suppose
    X1 is the number of Heads in 5 tosses of a fair coin, and X2

    is the number of Tails in
    the same 5 tosses. Which of the following
    statements are true, and which false?
    (a)
    X1 and X2 are independent
    (b)
    E(X1 + X2)= 5
    (c)
    X1 + X2 = 5
    (d)
    Var(X1 )= Var(X2 )
    (e) The correlation between X1 and X2 is -1
    (f)
    E(X1X2 )= E(X1 )(fX2 )
    (g) Taken individually, X1 and X2 have the same distribution
    (h)
    Var(X1 + X2 )= 0

    can you explain the answers as well please

    B
    can you explain the
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by hello123 View Post
    E3. Suppose
    X1 is the number of Heads in 5 tosses of a fair coin, and X2


    is the number of Tails in
    the same 5 tosses. Which of the following
    statements are true, and which false?
    (a)

    X1 and X2 are independent Mr F says: X1 + X2 = 5 so what do you think ....?
    (b)

    E(X1 + X2)= 5 Mr F says: X1 + X2 = 5 so what do you think ....?
    (c)

    X1 + X2 = 5 Mr F says: X1 + X2 = 5 so what do you think ....?
    (d)

    Var(X1 )= Var(X2 ) Mr F says: Refer to your answer to (g). So what do you think ....?
    (e) The correlation between X1 and X2 is -1 Mr F says: X1 + X2 = 5 so what do you think ....?
    (f)


    E(X1X2 )= E(X1 )(fX2 ) Mr F says: True only if X1 and X2 are independent .... So what do yuo think ....?
    (g) Taken individually, X1 and X2 have the same distribution Mr F says: Have you thought abut the distribution that each follow?
    (h)


    Var(X1 + X2 )= 0 Mr F says: See your answer to (d) ....

    can you explain the answers as well please

    B
    can you explain the

    You need to show a bit more effort here. What are your thoughts? Where do you get stuck?

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: April 12th 2011, 10:13 AM
  2. AP prob
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: May 6th 2010, 09:53 PM
  3. Prob-Value
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: August 25th 2009, 04:49 AM
  4. Log Prob.
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 3rd 2009, 04:14 PM
  5. prob
    Posted in the Calculus Forum
    Replies: 1
    Last Post: December 2nd 2007, 09:00 AM

Search Tags


/mathhelpforum @mathhelpforum