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Math Help - standard normal distribution

  1. #1
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    Arrow standard normal distribution

    I have to find what separates the top 5% and the bottom 5% of the distribution. Mean is 9.75 and Standard dev is .08

    I found that: -1.645= x - 9.75/ .08

    I am terribly stuck as I already had found the area which was .95 looking at my chart of Positive and Negative z-scores but don't remember how to exactly find x.
    I need some enlightenment, thanks so much. oH and do I have to draw the bell shaped curve as well?
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  2. #2
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    Quote Originally Posted by alexM0tts View Post
    I have to find what separates the top 5% and the bottom 5% of the distribution. Mean is 9.75 and Standard dev is .08

    I found that: -1.645= x - 9.75/ .08

    I am terribly stuck as I already had found the area which was .95 looking at my chart of Positive and Negative z-scores but don't remember how to exactly find x.
    I need some enlightenment, thanks so much. oH and do I have to draw the bell shaped curve as well?
    Top 5%, P(z)=0.95. This equals to 0.95-0.5 = 0.45.
    I looked in the table for area = 0.45 and found z=1.645

    z=\frac{x-9.75}{0.08}
    x=(1.645)(0.08)+9.75

    I cannot remember everything I have learned. That's why I peek in to remind me of it so that I could do well as I go upward.
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