Records indicate that the mean shelf life of a 5-gallon jug of chlorine is 2,160 hours (90 days). As an experiment, Holdlonger was added to the chlorine to find whether it would increase the shelf life. A sample of nine jugs of chlorine had these shelf lives (in hours):
(These are the results of the nine samples)
2,159 2,170 2,180 2,179 2,160 2,167 2,171 2,181 2,185
At the .025 level, has Holdlonger increased the shelf life of the chlorine better than before?
Any help would be greatly appreciated.