Posted by jr on Monday, October 29, 2012 at 4:01pm.
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 (σ = 1050), how large of a sample is needed to be accurate within $200 (E = 200)? That is, find n.

statistics  MathGuru, Tuesday, October 30, 2012 at 6:25pm
Formula:
n = [(zvalue * sd)/E]^2
...where n = sample size, zvalue will be 1.96 using a ztable to represent the 95% confidence interval, sd = 1050, E = 200, ^2 means squared, and * means to multiply.
Plug the values into the formula and calculate the sample size. Round your answer to the next highest whole number.
I hope this will help get you started.

statistics  Anonymous, Thursday, November 21, 2013 at 6:51am
105.88

statistics  Jack, Friday, October 24, 2014 at 6:18pm
105.88
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