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Confidence interval and sample size

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A manufacturer wishes to estimate the reliability (in months) of a certain product. An estimate of the population standard deviation from a previous sample was 12 months. If the manufacturer desires to be within 4 months of the true value with approximately 80% confidence, what should the sample size be?

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The solution provides step by step method for the calculation of Confidence interval and sample size. Formula for the calculation and Interpretations of the results are also included.

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Confidence Interval for the Mean
A manufacturer wishes to estimate the reliability (in months) of a certain product. An estimate of the population standard ...

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