Retirement Plan to take probabilities into account (Finance)

Hi, I am looking for someone to help with one specific exercise. My professor is not the best to explain and I am learning everything online… so it is kind of difficult to catch up on everything with his bad internet connection. 

This assignment has to be presented JUST USING EXCEL with the formulas the assignment required. I am attaching the example of the exercise with the formula, but some changes in the information (the file is in word, but again it has to be present in excel format)