How to do this hypothesis testing question?

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 6.33 6.50 5.22 3.56 6.76 7.98 4.82 7.96 4.54 5.09 6.46
((My calculation: sample mean#=5.6875# and sample standard deviation #=1.580368916# ))