Final answer:
The correct equation should represent a decreasing temperature over time since it's a refrigerator graph. Options c and d show this decrease, but without more information, we can't definitively choose between them. Option c is more likely as it implies a non-negative starting temperature.
Step-by-step explanation:
The student's question asks for the correct equation to represent a graph of the temperature T (degrees Fahrenheit) in a refrigerator t hours after midday. Considering that temperatures in a refrigerator should generally decrease over time if not being cooled actively, the best mathematical model would be one that shows a decrease in temperature as time increases. Looking at the given options, the options that show a decrease in temperature with an increase in time are options c and d:
- c. T = -t + 5
- d. T = -t - 5
Both equations imply that temperature decreases with time since the coefficient of t is negative. However, without additional information regarding the starting temperature or how quickly the temperature drops, we cannot definitively determine which of these two equations is correct. In a real-world scenario, it would be unusual for the fridge temperature to be negative, so we would lean towards option c assuming that '5' represents the starting temperature degrees above some reference point.