Samsung manufactures cellphone with an average standby time of 10 hours between charges. The standby time of the cellphone is normally distributed. During the design stage, the quality engineering staff recorded 18 observations of the standby time of the cellphone. Using the observations below, is there evidence that the average standby time of a Samsung cellphones is not 10 hours? Use a level of signicance of .05 Observation 3 10.81 10.24 10.23 9.49 9.89 10.11 9 10.57