Final answer:
The required fire rating between an Assembly occupancy and Mercantile occupancy is 1 hour for wall assemblies and 3/4 hour (45 minutes) for doors.
Step-by-step explanation:
Between an Assembly occupancy and Mercantile occupancy, both wall assemblies and doors are required to have a fire rating. The fire rating indicates how long it can withstand exposure to fire without spreading. In general, a common fire rating requirement for wall assemblies between these two occupancies is 1 hour, while for doors it is 3/4 hour (45 minutes).