To determine the temperature the soup must reach in the next four hours to be cooled properly, let's follow the cooling guidelines set by food safety authorities like the FDA (Food and Drug Administration).
1. According to the FDA, cooked food should be cooled from 135°F to 70°F within 2 hours. This initial cooling process is crucial to reduce the temperature where bacteria can rapidly multiply. The food worker in this scenario has successfully cooled the soup to 70°F within the required 2 hours.
2. Once the temperature has reached 70°F, the next guideline states that the food should be further cooled from 70°F to 41°F within an additional 4-hour period. This ensures that the food is brought down to a safe temperature where bacterial growth is significantly slowed or halted.
The target is to reach the final temperature of 41°F from 70°F within four more hours.
Reviewing the options:
a. [tex]\(41^\circ F \left(5^\circ C\right)\)[/tex]
b. [tex]\(45^\circ F \left(7^\circ C\right)\)[/tex]
c. [tex]\(51^\circ F \left(11^\circ C\right)\)[/tex]
d. [tex]\(55^\circ F \left(13^\circ C\right)\)[/tex]
Given the guidelines for safe cooling, the correct temperature the soup must reach within the next four hours is [tex]\(41^\circ F (5^\circ C)\)[/tex], as this temperature ensures compliance with food safety standards.
Thus, the answer is [tex]\( \boxed{41^\circ F \left(5^\circ C \right)} \)[/tex].
