The weekly earnings of middle managers in a large corporation are approximately normally distributed with a standard deviation of 36 dollars. A researcher wishes to estimate the mean weekly earnings. Find the sample size needed if she requires a 95% degree of confidence that the sample mean will not differ from the population by more than 3 dollars.

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Degree of confidence

The weekly earnings of middle managers in a large corporation are approximately normally distributed with a standard deviation of 36 dollars. A researcher wishes to estimate the mean weekly earnings. Find the ...

Solution Summary

The solution is a step-by-step explanation of how to solve the problem. It includes the formula for a confidence interval.

Q1: Why does thesample size play such an important role in reducing the standard error of the mean? What are the implications of increasing thesample size?
Q2: Why might one be interested in determining a sample size before a study is undertaken? How do population variability and a level of certainty affect the size of

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C= 0.90, s,=8.7, and E=2
Assume that the preliminary sample has at least 30 members.
n=___ (round to the nearest whole number)

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