A local pizza restaurant and a local branch of a national chain are located across the street from a college campus. The local pizza restaurant advertises that they deliver to the dormitories faster than the national chain. In order to determine whether this advertisement is valid, you and some friends have decided to order 5 pizzas from the local pizza restaurant and 5 pizzas from the national chain, all at different times. The delivery times in minutes are shown below.
Local Chain
16.8 22.0
11.7 15.2
15.6 18.7
16.7 15.6
17.5 20.8
Do the data provide sufficient evidence to conclude that the mean delivery time for the local pizza restaurant is less than the mean delivery time for the national pizza chain? Conduct hypothesis test using ?=.05.