If you had 5 dollars and 2 hours, how would you make as much money as possible?

1. Used a device to measure the tire pressure and materials to build the booth and signs. Did they cost less than $5? Maybe. Did it take less than 2 hours to create the booth, the signs, and perform the services? Unlikely.

2. Well done on finding something you can acquire for free and then sell. However: did they make the reservations at 6pm and then sell them before 8pm? If not, the process of making the money took more than the 2 hours allotted.

3. You had two hours. Instead, you spent 2 hours talking to an advertising company and then a week later you sold 3 minutes of your time. Total time used to make $650: a week. In the real world you can't just discount lead time and idle time; that's a mistake made by a lot of starving contractors.

The point of the puzzle is to work inside the constraints. "Thinking outside the box" is a great skill and all, but basically all these teams are doing is finding creative ways of breaking the rules. It means the puzzle isn't "make the most money in 2 hours with $5", it means the puzzle is "find out how far you can stretch these rules without being disqualified". Points for creativity, sure, but that wasn't the problem.

Personally I found the latter 2 solutions pretty unimaginative in ignoring the $5. If the exercise is to maximise the $5 (a much harder task it seems) then they seem to have failed.

I don't need to imagine. Most of the conferences I've been to work this way.

There are many ways to look at this. One is to note that, if I needed a job, I would probably pay cash money to attend a series of 3-minute commercials by companies that were looking to hire interns. Indeed, this is a lot of what Stanford students are paying tuition for. In the building next door to your college classroom is a job placement office that specializes in exactly this. So I'm kind of dubious about the assertion that this is some kind of terrible disservice to the students.

Another way to look at it: "sustainable growth" is highly overrated. It's not merely that it wasn't a criteria of the original problem -- which it wasn't -- but also that judging what is and isn't "sustainable" is an exercise in predicting the future. And, like all exercises in predicting the future, it tends to miss a lot of the good stuff. You find yourself saying things like "This business plan won't scale past the first 5000 customers!" or "If Netflix catches on, Blockbuster will get into the business and crush Netflix like a bug!" or "How could I ever make a million dollars doing something this trivial?" or "How can Twitter succeed after the open-source open-protocol Twitter Substitute comes along, as it surely will, any minute now?" [1]

But the most obvious conclusion is: Just because you can't do it twice doesn't mean it isn't worth doing once. If I were a student in that class, I would surely have been happy to sit through a three-minute presentation, though I'm not sure I would have heard much of it, because I would have been too busy rolling on the floor with laughter at the scope of the other students' awesome hack. But, yeah, it won't work a second time. Everybody knows the punch line now.

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[1] Hey, if people didn't believe stuff like this I wouldn't see it pop up on HN every three months, like clockwork.