Final answer:
At most, 16 average-sized adults can safely ride the elevator at the same time.
Step-by-step explanation:
The maximum weight capacity of the elevator is 2,500 lb. To find out the maximum number of average-sized adults that can safely ride the elevator, we divide the maximum weight capacity by the weight of a single average adult. 2,500 lb / 150 lb = 16.67. Since we can't have a fraction of a person, we can conclude that at most, 16 average-sized adults can safely ride the elevator at the same time.