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    stuck on a question guy need help pleeeeeaaaaase! :eek3: :eek3:

    a geometric series has common ratio 0.9. what is the smallest number of terms required for the sum of the series to be greater than 99.9% of the sum of infinity

    any ideas? would like working out too please

    Work out the sum to infinity using \Sigma_N =\frac{a}{1-r} where N=infinity.
    Multiply it by 0.99 to get 99%

    Use the equation \Sigma_n=\frac{a(1-r^n)}{1-r}
    to find n, where \Sigma_n is 99% of the sum to infinity.
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Updated: January 29, 2010

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