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Math Help - Standard deviation stuck

  1. #1
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    Standard deviation stuck

    Hai ... i still stuck for the following questio. for your info i already do the calculation & my ans is 88.25 or 88.75.something wrong maybe on my calculation.

    Question:
    The standard deviation of 6,9,8,x and 12 is 2. Calculate the value of x.

    tq for your time and help
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  2. #2
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    Quote Originally Posted by nikk View Post
    Hai ... i still stuck for the following questio. for your info i already do the calculation & my ans is 88.25 or 88.75.something wrong maybe on my calculation.

    Question:
    The standard deviation of 6,9,8,x and 12 is 2. Calculate the value of x.

    tq for your time and help
    Substitute the given data into the usual formula for standard deviation. Please show your working and where you get stuck.
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  3. #3
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    Quote Originally Posted by mr fantastic View Post
    Substitute the given data into the usual formula for standard deviation. Please show your working and where you get stuck.
    tq for your response sir.. attached is my solution.. i don't where is wrong..
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  4. #4
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    Quote Originally Posted by nikk View Post
    tq for your response sir.. attached is my solution.. i don't where is wrong..
    Does your answer satisfy the following:

    s^2 = \frac{1}{5-1} \left(6^2 + 9^2 + 8^2 + x^2 + 12^2\right) - \frac{5}{5-1} \left( \frac{6 + 9 + 8 + x + 12}{5}\right)^2
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  5. #5
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    tq

    Quote Originally Posted by mr fantastic View Post
    Does your answer satisfy the following:

    s^2 = \frac{1}{5-1} \left(6^2 + 9^2 + 8^2 + x^2 + 12^2\right) - \frac{5}{5-1} \left( \frac{6 + 9 + 8 + x + 12}{5}\right)^2
    i will check..tq
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