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Statistics Question - Normal Distribution

  1. May 6, 2009 #1
    Statistics Question - Normal Distribution SOLVED

    1. The problem statement, all variables and given/known data
    Hey, the question is shown in the attached document.

    2. Relevant equations
    Mean = 79 Standard Deviation = 12

    3. The attempt at a solution
    I dispise these questions, and i'm failing to grasp them at all.

    I've done the first two parts fine, but it's part c i'm struggling on.

    I've tried using the z function getting me to;

    P (Z [tex]\leq[/tex] [tex]\frac{b}{12}[/tex] ) - P ( Z [tex]\leq[/tex] [tex]\frac{-a}{12}[/tex] ) = 0.375

    But i've got no idea what i'm doing :/ this question has totally thrown me, all of the methods i've used replacing the 2nd equation into the first have given me useless answers, I can usually do these questions fine, but i'm struggling here, any help would be great!

    Attached Files:

    Last edited: May 6, 2009
  2. jcsd
  3. May 6, 2009 #2
    never mind, got it, ridiculously easy AGAIN
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