Since you start with saying I am working on a homework problem and I am trying to use the What-If Analysis. I don't know if I do not have enough values or if I am not inputting them correctly, it seems reasonable to assume that you've made some tries already.
Why don't you upload what you've done so far so I or somebody else can comment on what you've done and not have to start from scratch.
Also, since you acknowledge it's a homework problem, I'm sure you'll agree that it makes more sense that you do most of the work....so if I end up being the one commenting, I might just offer one or two suggestions like...(1) write your formulas so they use a separate field called "assumed growth rate for S&P 500 overall" or something like that. (2) You clearly need a variable (better as a separate cell referenced in your "What-if" formulas) that would reflect that vague thing called "volatility".... and so forth.