A courier service advertises that its average delivery time is less than 6 hours for local deliveries. A random sample of times for 12 deliveries to an address across town was recorded. These data are shown here. Is this sufficient evidence to support the courier's advertisement, at the 5% level of significance? 3.03, 4.33, 6.50, 5.22, 3.56, 6.76, 3.98, 4.82, 3.96, 4.54, 5.09, 6.46