Results 1 to 2 of 2

Math Help - Normal distribution

  1. #1
    Junior Member
    Joined
    Oct 2008
    Posts
    29

    Normal distribution

    Hey guys, was wondering if you guys could help me out with this, been ok so far with my Stats at Uni but not sure what to do with these examples, can anyone help me or just give me the formula I'm meant to use for each? Need to do this by tomorrow morning, only reason I'm posting in this section.

    a) Random Variable X has N(2,3) distribution
    i) Evauluate P (X>3)
    ii) P(-1<X<4)
    iii) Find a such that P([X-2]<a)=0.1

    b) X and Y are now independent with N(1,5) and N(5,1)
    i) Evauluate P(X<0, y>6)
    ii) P(-3<3X - Y<0)
    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 Mathsnewbie View Post
    Hey guys, was wondering if you guys could help me out with this, been ok so far with my Stats at Uni but not sure what to do with these examples, can anyone help me or just give me the formula I'm meant to use for each? Need to do this by tomorrow morning, only reason I'm posting in this section.

    a) Random Variable X has N(2,3) distribution
    i) Evauluate P (X>3)
    ii) P(-1<X<4)

    Mr F says: In each case you convert the value of X to a z-value using the formula {\color{red}Z = \frac{X - \mu}{\sigma}}. Then use your Four-Figure Standard Normal Distribution Tables. Is 3 the variance or the standard deviation of X?

    iii) Find a such that P([X-2]<a)=0.1

    Mr F says: What does [X-2] mean .... Do you mean |X-2|? In any case, use your standard normal tables in reverse.

    b) X and Y are now independent with N(1,5) and N(5,1)
    i) Evauluate P(X<0, y>6)

    Mr F says: Calculate {\color{red}\Pr(X < 0) \cdot \Pr(Y > 6)}.

    ii) P(-3<3X - Y<0)
    ii) You need to integrate the joint pdf over the region of the XY-plane defined by -3 < 3X - Y < 0 \Rightarrow 3X < Y < 3x + 3.

    Given you're earlier questions, I would concentrate on understanding and answering those basic questions before worrying about this one.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: December 27th 2011, 01:08 PM
  2. normal distribution prior and posterior distribution proof
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: March 9th 2011, 06:12 PM
  3. Replies: 2
    Last Post: March 29th 2010, 02:05 PM
  4. Replies: 3
    Last Post: February 6th 2009, 03:59 AM
  5. Replies: 1
    Last Post: April 20th 2008, 06:35 PM

Search Tags


/mathhelpforum @mathhelpforum