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    Jennio2875's Avatar
    Jennio2875 Posts: 3, Reputation: 1
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    #1

    Jun 12, 2009, 06:20 AM
    Statistics - standard deviation
    Hi there... I need help on a question... here goes the problem
    Assume the average salary for a worker in the US is $27,500 and that the annual salaries for Americans are normally distributed with a STANDARD DEVIATION equal to $6,250. What percentage of Americans earn below $18,000?

    Help with starting the problem would be great
    FlyYakker's Avatar
    FlyYakker Posts: 378, Reputation: 41
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    #2

    Jun 12, 2009, 07:12 AM

    I stand to be corrected but if I remember correctly, you should already know what percetages are covered by one, two, three SD's, etc. in all cases, and I suspect you work more or less based on that thought process.
    Jennio2875's Avatar
    Jennio2875 Posts: 3, Reputation: 1
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    #3

    Jun 12, 2009, 07:15 AM

    I still don't get it
    galactus's Avatar
    galactus Posts: 2,271, Reputation: 282
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    #4

    Jun 12, 2009, 07:38 AM
    Just use the formula , then look up the corresponding value in the body of the z table.
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