The U.S. Department of Labor Bureau of Labor Statistics posts a table of average hourly wages paid to production workers on private nonfarm payrolls by major industry. The following data were taken from their website on May 18, 2005.

Average Hourly Earnings of Production Workers Year Jan Feb Mar Apr to Dec 1995 14.37 14.59 14.62 14.66 14.76 to 2005 19.24 19.31 19.35 19.38

••• Remainder of data on Student’s Suite CD-ROM Source: http://data.bls.gov/cgi-bin/surveymost

a. At the 0.05 level of significance, does the evidence provide sufficient reason to reject the claim that there is no difference in the mean hourly wages paid by month? Show graphical evidence to visually support your conclusion.

b. At the 0.05 level of significance, does the evidence provide sufficient reason to reject the claim that there is no difference in the mean hourly wages paid each year? Show graphical evidence to visually support your conclusion.