Final answer:
The payment method used by Cal's factory is a fixed-ratio reinforcement schedule, with rewards given after a set number of widgets are assembled.
Step-by-step explanation:
The owners of the factory are using a fixed-ratio schedule of reinforcement to pay Cal. A fixed-ratio reinforcement schedule means there is a set number of responses, or in Cal's case, widgets assembled, that must occur before the behavior is rewarded. In this scenario, for every 100 widgets Cal assembles, he is given a $10 reward. This is different from a variable ratio schedule, where the number of responses needed for a reward varies, or the fixed and variable interval schedules, where the rewards are based on time intervals rather than the quantity of work done.