The postal service sorts mail as Priority Mail Express, Priority Mail, First-Class Mail, or Standard Mail. Over a period of 3 weeks, 18 of each type were mailed from the Network Distribution Center in Altanta, Georgia, to Des Moines, Iowa. The total delivery time in days was recorded. Minitab was used to perform the ANOVA. The results follow:

Using the ANOVA results, compare the average delivery times of the four different types ofmail.

Source DF Factor 3 30.298 10.099 11.90 0.000 Error 68 57.705 0.849 Total 71 88.003 MS S=0.9212 R-Sq=34.434 R-Sq (adj ) =31.549 Level Priority Mail Express 18 1.0694 0.7652 Priority Mail First-Class Ma11 standard Mail Mean StDev 18 1.7210 1.0829 18 2.5211 0.9097 18 2.6840 0.8991 Priority Mail Express subtracted from Lower Center Upper 0.0389 0.6516 1.2644 Priority Mail First-Class Mail 0.8390 1.4517 2.0645 Standard Mail 1.0018 1.6146 2.2273 Priority Mail First-Class Mail Standard Mail 0.0 1.0 2.0 Priority Mail subtracted from: Lower Center Upper First Class Mail 0.1874 0.8001 1.4128 0.3502 0.9629 1.5757 Standard Mail First-Class Mail Standard Mail 0.0 2.0 First-class Mail subtracted from: Lower Center pper Standard Mail -0.4499 0.1628 0.7756 Standard Mail 2.0