The interviewer slides a sheet of paper across the table. 'How many golf balls fit in a school bus?'
Your first instinct: this is ridiculous. Who cares? When would I ever need to know this?
Here's what the interviewer actually wants to see: Can you break a messy, ambiguous problem into logical pieces? Can you make reasonable assumptions and explain your thinking? Can you do basic math under pressure without freezing?
Market sizing cases aren't really about golf balls or school buses. They're about showing you can think structurally when you have no data and no obvious answer. And that's exactly what you'll do on client projects, every single week, when someone asks 'Should we enter this market?' and you have to figure out if it's worth $50M or $500M.
The good news: you don't need special domain knowledge. You need a thinking process. I've seen liberal arts majors crush market sizing cases because they thought clearly, and finance PhDs bomb because they overthought it.
This lesson walks through ONE complete market sizing case in detail, showing you the thinking process from start to finish. Then you'll practice on your own to build the instinct.