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Thread: normal distribution z score problem

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    normal distribution z score problem




    QUESTION:

    A normal distribution has a mean of 70 and a standard deviation of 15. Determine the value above which 80 percent of the values will occur. (Round z-score computation to 2 decimal places and the final answer to 2 decimal places.)



    Where do I look for the Z value for 80%? I know that the formula to use is x = zs +u BUT I have no idea where to find the 80% z value. Please help. Thank you.

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    Re: normal distribution z score problem


    Always draw a picture of the normal curve with the data on it. Shade in the area you are dealing with. Have a rough guess at the answer. Explore the Excel function =NORMINV(something goes in here,75,15)

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