To minimize the potential for gastrointestinal disease outbreaks, all passenger cruise ships arriving at U$.$S$.$ ports are subject to unannounced sanitation inspections. Ships are rated on a scale of $0$ to $100$ points, depending on how well they meet the Centers for Disease Control and Prevention sanitation standards. In general, the lower the score, the lower the level of sanitation. A sample of international cruise ships was selected and yielded the sanitation inspection scores that can be found at the file: shipsanitation.txt $($which is available on our Quercus webpage$).$

Please do the following:

Step $1.$ Create a folder named sta$258.$

Step $2.$ Save shipsanitation.txt in the folder you created in Step $1.$ You will find shipsanitation.txt in our Quercus page.

Step $3.$ Launch R$.$

Step $4.$ Change working directory to sta$258($folder created in Step $1).$

Step $5.$ To import data into R$,$ please type the following command:

sanitation.score$=$read.table$($file$=$"shipsanitation.txt$",$header$=$TRUE$)$;

The most common measure of center is the ordinary arithmetic average, or mean. Find it for this data and provide its numerical value. Round your final answer to four decimal places.