Answer :
Which promotion exemplifies the use of a fixed-ratio schedule of reinforcement? A café prints "you are a winner" on a random one-twelfth of its coffee lids; patrons receiving such a lid can redeem it for a free beverage. A fixed-ratio schedule of reinforcement, which a response is reinforced when there is a set number of responses. Every set number of people purchasing the coffee have a chance to win a free beverage.