Final answer:
No, x and y are not in a proportional relationship because the ratio of y to x is not constant.
Step-by-step explanation:
To determine if x and y are in a proportional relationship, we need to check if the ratio of y to x is constant. In this case, y represents the temperature in °F and x represents the number of hours after midnight. The temperature decreases 2°F every 12 hours, which means that for every 12-hour interval, the temperature decreases by 2°F. Therefore, the ratio of y to x is not constant, indicating that x and y are not in a proportional relationship.