Statistics

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Having problems reading the z-table. I don't understand how .1500% equates to a 1.04 z-score

Thank you for your help

  • Statistics -

    The .15% is the tail end of the probability distribution.

    Probability distributions are such that the total area is 1.0 from Z=-∞ to Z=+∞.
    For the normal distribution, Z=0 is at 0.5, which means that the probability of a variable falling above 0 is exactly that of falling below 0.

    Here you're looking for the value of Z for which the probability of a variable falling above Z is 0.15, and below is 0.85. So look up the table (below) for Z such that the entries of the table is 0.85, which corresponds to a Z=1.04.

    Also, check the little sketch in the following table:
    http://www.math.unb.ca/~knight/utility/NormTble.htm

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