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Math Help - What am I doing wrong with this normal probability distribution?

  1. #1
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    What am I doing wrong with this normal probability distribution?

    Find z if the area to the left of z is 0.2981.

    I subtract .5-.2981 and get .2019. When I look that up in the table, I get 0.53 but I was told that isn't right. I'm not sure what I am doing wrong.
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  2. #2
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    I would consider P(z<0.2981) = 1 - P(z>0.2981)
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  3. #3
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    OK, so when I do that this is what I come up with:

    1-(0.5 - 0.2981) = 0.7981.

    That doesn't look right to me because I can not find the value of z in the chart because the chart only goes up to 0.4999. I have no idea what I am doing here.
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  4. #4
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    OK, it dawned on me that maybe 0.53 is actually correct but since it is to the left, it would be -0.53. Am I off base here or does that sound right to anyone?
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  5. #5
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    Have a look at

    Z table - Normal Distribution

    Spoiler:
    P(z<0.2981) \approx 0.617187
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  6. #6
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    I used that calculator and came up with -0.5299, so I guess I was right with -0.53. Thanks for your help!
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