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Math Help - Normal Distributions

  1. #1
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    Normal Distributions

    My last problem for the day ^_^

    Suppose X=SAT score and X~N(1020,?). Suppose we take a SRS of 16 SAT scores and find s=100. Find P(xbar<950).

    Answer choices:

    A) 950
    B) .7527
    C) .9933
    D) .0067
    E) 0
    F) .2473
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  2. #2
    MHF Contributor matheagle's Avatar
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    Use a t with 15 dfs.

    P(\bar X<950)=P\left( {\bar X-\mu\over s/\sqrt{n}} < {950-1020\over 100/4}\right)

    P(t_{15}<-2.8)=.006730

    from http://www.danielsoper.com/statcalc/calc08.aspx
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