a union of restaurant and food service workers would like to estimate the mean hourly wage, mean, of foodservice workers in the US. the union will choose a random sample of wages and then estimate mean 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 $0.45 of mean? Suppose that the standard deviation of wages of foodservice workers in the US is about $2.15.