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Math Help - final score (X) when given SD, M, and variation

  1. #1
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    final score (X) when given SD, M, and variation

    Hi,

    Wondering how you would go about figuring the following problem.

    N = 10, M = 20, SD = 2

    Nine of the raw scores have a variation of +12, given the rest of the info on the sample, what is the tenth raw score?

    Thank You
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  2. #2
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    Re: final score (X) when given SD, M, and variation

    Four possible answers were given: 18, 12, 6, 2.

    Also, what is meant by the 9 variation scores adding up to +12 is for example.

    22 - 20 = 2
    18 - 20 = -2
    17 - 20 = -3
    23 - 20 = 3

    etc., and the total of X-M for the 9 raw scores was +12

    Is this question even possible to figure out? Wouldn't you need at least the Sum of Squares for the 9 raw scores?
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  3. #3
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    Re: final score (X) when given SD, M, and variation

    *the sum of deviation scores for the 9 raw scores = +12

    If the question did not mention the SD and simply asked what the tenth score is if the sum of deviation scores for the other 9 = +12 then the answer would be 8, because (X-M=deviation score) so (8-20=-12) and all deviation scores add up to 0. I'm thinking the question is not possible, because if you use 8 as the tenth raw score then that results in a squared deviation of 144 (-12 x -12) which by itself is too great to produce a small SD=2. ??
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