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Math Help - [GCSE-O] Number Sequence And Standard Deviation

  1. #1
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    [GCSE-O] Number Sequence And Standard Deviation

    Hi all. I am doing revision for Elementary and Additional Mathematics and need help with the following question for my elementary mathematics GCSE O Level.
    Thank you.

    I hope someone is able to help me with the following questions. Thank you very much


    1) Find the next two value of the sequence

    7/8 , 2/3 , 1/2 , 4/11 , 1/4


    I can't figure out any formula for this.
    I tried using the arithmetic and geometric sequences and series, but I still can't find it.


    2) A data has the following value, a, b, c, 4 and 8. The mean for a, b, and c, is 8

    the standard deviation for a b and c is sqrt(7)


    find the standard deviation for the 5 values.


    I did up till (a-8)2 + (b-8)2 + (c-8)2 = 21


    I found the mean for the 5 values is 7.2.


    Thank you for reading and the help!
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  2. #2
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    Re: [GCSE-O] Number Sequence And Standard Deviation

    Hello, mynameiscosine!

    \text{(1) Find the next two values of the sequence: }\:\frac{7}{8},\;\frac{2}{3},\;\frac{1}{2},\;\frac  {4}{11},\;\frac{1}{4}\,\hdots

    This requires a "trick" that you haven't thought of . . .

    Re-write the fractions: . \frac{7}{8},\;\frac{6}{9},\;\frac{5}{10},\;\frac{4  }{11},\;\frac{3}{12},\;\hdots

    Got it?
    Thanks from mynameiscosine
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  3. #3
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    Re: [GCSE-O] Number Sequence And Standard Deviation

    @Soroban

    Ohhh!

    I should have seen this pattern. You made it so easy! lol
    The next two number should be

    2/13, 1/14

    Am I right?

    Thank you very much!

    How about the second question for standard deviation?
    Thanks again!
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