Answer:
46° Fahrenheit
Explanation:
Center line can be said to be the X double bar. X double bar is the average value we have across all components we're considering. In this question, the X double bar is already given as 960 bottles (if you multiply 120 days by 8 bottles per day) and that it is 46 degrees Fahrenheit.
As such, there exist no reason to want to or have to solve for anything since it's already given.
Therefore the Centre line is 46 degrees Fahrenheit, same as what is given in the question.