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Homework Help: 1st year stats, empirical rule- range of values

  1. Jan 26, 2006 #1
    I am taking 1st year stats at university, and I have lab questions I am supposed to answer. I am VERY confused.
    My data set is:
    53, 33, 25, 63,26, 64, 32, 21, 45, 64, 38
    I calculated the mean:42.182
    the sample variance:272.147
    The range:43
    The percentile rank of the data value 45: 59th
    The value corresponding to the 80th percentile:63
    Outliers: none
    Standard deviation: 16.497
    Now I am asked: according to the empirical rule, if the above data is normal find the range of values in which approximately 68% of the data will lie. I know the empirical rule applies only to bellcurved graphs... but this would not produce a bell curve correct? So would there be an answer?

    Then they ask: What is the actual percentage of the data that lie in your interval from above.?

    Any help is appreciated thanks!
  2. jcsd
  3. Jan 26, 2006 #2


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    Science Advisor

    You should know that if the data is normal then about 68% of the data lies within 1 standard deviation of the mean. They expect an incorrect answer for the first part--they are saying, what if it were normal, then what would the answer be.
  4. Jan 26, 2006 #3
    THANKS! I realize now what they are asking and got the answer:

    mean-standard deviation=25.685
    mean+standard deviation= 58.679

    So for the next part: What is the actual percentage of the data that lies in the intervals from previous question.

    So would I do, which of these intervals: 22 25 26 32 33 38 45 53 63 64 64 will lie between 25.685 and 58.679??
    which is 26, 32, 33, 38, 45, 53
    so: 6/11 fall within those intervals, so 6/11 * 100 = 54.54% of the data lie between these intervals.
    THANKS again.
  5. Jan 26, 2006 #4


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    Science Advisor

    Yes, that's correct.
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