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Math Help - Probability/Z-Score Question

  1. #1
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    Probability/Z-Score Question

    For a normal distribution with a mean of 7.5 and a variance of 9, find the following:

    P(x greater than or equal to 8.5)

    =1 - P(Z less than or equal to (8.5-7.5)/3)

    =1 - P(1/3)

    1/3 on the z-score table is 0.6293

    =1 - 0.6293

    =0.3708

    Is that correct? If not, what am I doing wrong? All help appreciated!
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  2. #2
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    Re: Probability/Z-Score Question

    Quote Originally Posted by youngb11 View Post
    For a normal distribution with a mean of 7.5 and a variance of 9, find the following:

    P(x greater than or equal to 8.5)

    =1 - P(Z less than or equal to (8.5-7.5)/3)

    =1 - P(1/3)

    1/3 on the z-score table is 0.6293

    =1 - 0.6293

    =0.3708

    Is that correct? If not, what am I doing wrong? All help appreciated!
    Your answer is correct, not withstanding the lack of the use of correct notation in several places. But surely you're able to check your answer yourself using an on-line normal cdf calculator (found using Google)?
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