Weighted Average: from requirements to implementation

Just a few days ago, I was given a very typical request to calculate common business measure: Weighted Average. Usually, business folks give their verbal explanation of the problem along with their way of calculation and provide us developers with at least a formula or an Excel spreadsheet that explains in detail what is required and how it’s solved by example. Since, almost all people who are new to MDX script struggle to tackle such requests, and because I was asked several times on how I did it, I decided to provide a step-by-step explained development process of converting Excel logic to a MDX implementation and to be able to show how a typical problem can be solved and even optimized to a certain extent.