Results 1 to 2 of 2

Math Help - confidence unknown

  1. #1
    Member
    Joined
    Nov 2006
    Posts
    139

    confidence unknown

    Independent random samples from 2 normally distributed populations give the following results

    n_x= 10 x=480 s_x=30
    n_y= 12 y= 520 s_y= 25

    A) If we assume that the unknow population variances are equal , what is the 90% confidence interval for the difference OF population means?

    B) If we assume that the unknow population variances are equal , what is the 90% confidence interval for the difference BETWEEN population means?

    OF vs. BETWEEN? Where is the difference? What is he asking? I just know a formula that is (x-y) + or - t* sqroot [(s2_p/n_x) + (s2_p/n_y) ]

    Help. Please.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Aug 2007
    From
    USA
    Posts
    3,110
    Thanks
    2
    I'm not sure what they are getting at.

    Wild guess?

    Difference OF |x-y|?

    Difference BETWEEN (x-y)?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Confidence Interval for unknown sigma
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: November 2nd 2009, 02:06 PM
  2. Confidence Interval, unknown stand dev
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: November 1st 2009, 07:32 PM
  3. Replies: 1
    Last Post: April 15th 2008, 07:13 PM
  4. Confidence interval-population standard deviation unknown
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: April 4th 2008, 07:25 PM
  5. Replies: 1
    Last Post: April 4th 2008, 10:39 AM

Search Tags


/mathhelpforum @mathhelpforum