Mean 450.29 STDEV 53.35 0.4648 Looking at the data related to the maintenance costs for the Buena buses, there is a difference between the manufacturers suggested costs and the actual mean costs found in the bus data. First, the manufacturer states that the average per moth cost is $455 per bus, however viewing the actual bus data from Buena, the mean cost is $450 this is $5 less per month than the manufacturer suggests. Along with this, there is a 46% that the sample mean will be less than Buena's in relation to normal probability