Thank you Clive and OldAIMGuy. Clive your example hits the nail on the head. This formula is useful specifically for the purpose of figuring out how much cash should be invested at any given time for a specific equity. That's what I was going for. Pure AIM by the book does not answer the question what percentage of cash should be invested for each stock. I don't think one ratio should apply to every situation, stock/ETF. Each stock's price range is different. And that's why, in my opinion, we need to allocate different amounts of cash for every equity.
Do you know of a better way to do this?