# Calculating the sample size given a significance level

A researcher is interested in estimating the average salary of teachers in a large urban school district. She wants to be 95% confident that her estimate is correct. If the standard deviation is $1050, how large a sample is needed to be accurate within $100?

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#### Solution Preview

Lower Limit = Mean - Z*Std Dev/n^.5

<br>Upper Limit = Mean + Z*Std ...

$2.19