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Math Help - Finding probablity using the standard normal distribution

  1. #1
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    Finding probablity using the standard normal distribution

    Can anyone help with the problems below? Please explain, if possible.


    Calculate the following probabilities:

    i. P(0 z 2.3)
    ii. P(0 z 1.68)
    iii. P(0.24 z .0.33)
    iv. P(-2.58 z 0)
    v. P(-2.81 z . -1.35)
    vi. P(-0.73 z 0.49)
    vii. P(z 1.7 )
    viii. P(z -0.95)
    ix. P( z - 1.96) x. P(-1.4 z 1.55)

    How do you work these out? I'm lost.
    Last edited by mr fantastic; April 15th 2009 at 01:06 AM. Reason: Moved from another thread
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  2. #2
    Senior Member Twig's Avatar
    Joined
    Mar 2008
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    Gothenburg
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    Hi

    You do pretty much the same thing for all of these.
    I assume you have some basic knowledge here, understandning that you
    have a normalized variable z, with mean 0 and standard deviation 1.

     P(0 \leq z \leq 2.3) can be calculated using a distribution table. (Google, wikipedia etc).

    In this you look up that the probability that  z \leq 2.3 is approximately 0.9893.

    But you have also that  0 \leq z .
    And  P(0 \leq z) = 0.5

    So 0.9893-0.5 = 0.4893
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