Need to know which formulae which has been used

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zorro
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Need to know which formulae which has been used

Postby zorro » Sun Jun 27, 2010 7:43 am

Question :

The average working-set size X of a program is normally distributed with the unknown mean and a known variance 2=81 . The program was executed 36 times and the average working set size for each run recorded. The sample mean was computed to be 100 page frames . Assuming successive runs of the program are independent, find the 95% confidence interval for the mean average working set size


Solution:

(100-1.96 * 9/6 , 100 + 1.96 * 9/6) = (97.06 , 102.94)

Need to know which formula been used in order to get this result?

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maggiemagnet
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Re: Need to know which formulae which has been used

Postby maggiemagnet » Sun Jun 27, 2010 11:08 am

If you're not sure what formula this is, try working backwards from the "sample" formulas they've given you. Which one uses in the numerator? Which one also uses in the denominator? :thumb:

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zorro
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Re: Need to know which formulae which has been used

Postby zorro » Tue Jul 06, 2010 2:53 am

maggiemagnet wrote:If you're not sure what formula this is, try working backwards from the "sample" formulas they've given you. Which one uses in the numerator? Which one also uses in the denominator? :thumb:

Thanks!!


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