Sample size calculation

A union of restaurant and food service workers would like to estimate the meanhourly wage, , of food service workers in the U.S. The union will choose a random sampleof wages and then estimate using the mean of the sample. What is the minimum sample size needed in order for the union to be 90% confident that its estimate is within $0.50 of ? Suppose that the standard deviationof wages of food service workers in the U.S. is about $2.15.

Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum whole number that satisfies the requirements).

This solution gives the step by step method for computing sample size for estimating population mean.