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# Minimum sample size required...?

Use the given information to find the minimum sample size required to estimate an unknown population mean u.

How many adults must be randomly selected to estimate the mean FICO (credit rating) score of working adults in a country? We want 95% confidence that the sample mean is within 3 points of the population mean, and the population standard deviation s 75.

The minimum sample size required is___ adults.

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- 1 decade agoFavorite Answer
Since z = (x_ - μ) / (σ/√n), sample size n can be computed as

n = [zσ /(x_ - μ)]²

For a 95% confidence level, |z| = 1.96.

Therefore, for σ = 75 and |x_ - μ| = 3,

n = (1.96 x 75 / 3)² = 2401

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