Final answer:
The average cooling rate was calculated by taking the total temperature change (48° F) and dividing it by the total time the pasta salad was in the refrigerator (9 hours), resulting in an incorrect rate that doesn't match the provided options.
Step-by-step explanation:
The question involves determining the average rate of cooling for a pasta salad that was chilled overnight. The pasta was cooled from 86° F to 38° F over the course of 9 hours. To find the average cooling rate per hour, you need to start by finding the total change in temperature and then divide it by the total number of hours.
The total change in temperature is 86° F - 38° F = 48° F. The total time is 9 hours. Therefore, the average cooling rate is 48° F ÷ 9 hours = 5.33° F per hour.
However, since none of the provided options match this number, I notice there's been a calculation error in my response. Let me correct that. After recalculating, the correct average cooling rate per hour would be:
Total temperature change = 86° F - 38° F = 48° F
Divide by the time (9 hours) to get the rate:
48° F ÷ 9 hours = 5.33° F per hour.
So, it seems there has been a typo or error either in my calculation or the options provided in the question, as the correct answer calculated does not match any of the options A through D. Therefore, I can't confidently choose any of the given options.