Question 1131856: A researcher wishes to estimate the mean amount of money spent per month on food by households in a certain neighborhood. She desires a margin of error of . Past studies suggest that a population standard deviation of is reasonable. Estimate the minimum sample size needed to estimate the population mean with the stated accuracy
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! To do this, one needs to know the sd, margin of error required, and the confidence.
if 95% confidence, the half-interval or margin of error, is 1.96*sd/sqrt(n), where n is the sample size and the sd is presumed known. If the sd is not known, one needs a t-value, a little more complicated but basically the same approach.
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