According to the U.S. Bureau of Labor Statistics, the average weekly earnings of a production worker in July 2011 were $657.49.Suppose a labor researcher wants to test to determine whether this figure is still accurate today. The researcher randomly selects 54 production workers from across the United States and obtains a representative earnings statement for one week from each. The resulting sample average is $673.58.

Assuming a population standard deviation of $63.90 and a 5% level of significance, determine whether the mean weekly earnings of a production worker have changed.