The Department of Labor would like to estimate the average weekly wages for U.S. adults with a margin of error equal to $20. Determine the sample sizes needed to construct a confidence interval for this estimate using the following confidence levels. Assume the population standard deviation for the weekly wage is $160.

a. 90%

b. 95%

c. 98%

d. Explain why the confidence level affects the sample size needed to obtain a particular margin of error.

AppendixLO1