How to approach a Data Science case study question?
This question (something I've asked variants of several times in interviews) has absolutely nothing to do with statistical or other quantitative procedures. What is being asked here is for an understanding of the overall data mining process itself.  The first thing to determine is what the definition of success. So you have to ask. The stakeholder usually will not volunteer this unless asked anyway. Then, depending on the answer describe the overall process for data mining based on this end goal.