horrible question

there are a lot of variables here.

Based on comparables is my guess (e.g., based on cost of non-magical, regular, usable by one person taxi license). Did interviewer have any estimates of current license costs, or how current taxi licenses are setup?

This is a pretty basic market-sizing question if you ask me. Estimate the amount of profit you could generate per year operating a cab 24/7. Revenue = Avg. $/cab ride x Avg. cab rides/hr x hrs/year. Cost = gas + cost of taxi/useful life + maintenance + insurance. Or something like that.

Na BigPicture.

Yeah, that's how I attempted to answer it, humblebot, but had a maths fail. It was cringeworthy, worst experience ever.

I actually disagree that it is the best way to answer the question; it is not a market sizing question imo. It is actually an investment question. I took it to be market sizing in my answer, but I was wrong. It is deceptively worded.

When asked to estimate the number of beds in the US or the weight of a plane, there is a definite answer. You try to get to a realistic number using analysis - even if your number is off, your thought process is what matters.

Here you would be wrong to bother to calculate what a taxi driver earns because your assumptions would be flawed and it would depend hugely depending on the taxi driver. The answer has to take into account 3 revenue streams - price for the journey, tips and advertising, not just one. You would be using analysis to arrive at an indefinite number with so many assumptions in the variable you put in to make the process redundant.

If I were to answer it again, I would say OK. I need to buy a taxi. So this is a big investment for me. I want that money back plus profit within 5 years. So I'm talking about my ROI. I would rent out the taxi, for sure, but you don't have to be a maths genius to work out that it would be useless to rent out the taxi 24/7 since the fares from nighttime will likely be very little and with a minimum wage for your drivers, you're just about breaking even.

So you start by thinking about your customer segment - taxi drivers. What your vehicle can provide them, what sort of taxi driver you're catering to, e.g. someone with knowledge and experience, not an ordinary joe unlicensed mini-cab driver. You get your value proposition straight. Then you start thinking about pricing from a ROI perspective. OK i need 60k for a taxi. If I charge 15k a year, then I make 75k in 5 years; 15k profit, and I might also be able to sell on my taxi for 30k. However here are the risks of my investment e.g. risk of not having the taxi rented out for say 50% of the year, the market for selling taxis in 5 years, the depreciation in your taxi etc.

Can my customer afford the 15k a year price point. And sure, THEN you could work out the revenue stream; but I would have just acknowledged it was flawed based on the above, and would have estimated the 15- advertising of say 2.5k, and tips of 10% of earnings, the taxi driver only has to cover a few thousand, which should be easily manageable on a range of incomes considering the opportunity cost of not being able to drive in the first place and the VPs I've put in place.

Given that, you acknowledge the subjectivity of the question and say hey I'd take x% of my year 1 revenue stream, e.g. 5%, which is x% of overall profit.

Just my thought.