SOLUTION: We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately σ=48.7. We would lik

Question 1156421: We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately
σ=48.7. We would like to be 95% confident that the esimate is within 2.5 of the true population mean. How large of a sample size is required?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
half-interval has to be with 2.5 of the mean.
so 2.5=z*sigma/sqrt In)
2.5 sqrt(n)=z*sigma
n=z^2*sigma^2/2.5^2
=1457.77 or 1458

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