Final answer:
The frequent flyer program is an example of a fixed ratio reinforcement schedule, as it rewards users with a free flight after a set number of responses (accumulating 25,000 miles).
Step-by-step explanation:
An airline offering a frequent flyer program where people earn a free flight after accumulating 25,000 miles exemplifies a fixed ratio reinforcement schedule. In this schedule, a set number of responses must occur before a behavior is rewarded.
This is in contrast to variable ratio, which requires an unpredictable number of responses, fixed interval, which provides reinforcement after a set amount of time, and variable interval, where reinforcement is given at unpredictable time intervals. A fixed ratio schedule like the frequent flyer program incentivizes a high response rate, with participants aiming to collect miles consistently until they hit the target that triggers the reward - their free flight.