ChetOS.net

I was perusing a book at Barnes and Noble over the weekend.  The book was about software development as an occupation (as opposed to the technical aspects).  Once chapter was about interviewing and some of the non-technical questions that people get from organizations like Google.

These are questions that you are not expected to know the answer to, but are intended to show your thought process.

There was only one question that I really looked at, it was "How many gas stations are in the United States?".  The example for how to come to an answer analyzed the question from the aspects of average number of cars served per hour.  He came up with 33,000.  He also said that to be considered correct, you should be within an order of magnitude (so his answer is close enough if the actual answer was closer to 33,000 than it it was to 330,000).

I gave it some thought the other day while I was driving, and I went about it in a different fashion.

Saint Cloud has a population right around 30,000.  After some thought, I determined that there were 12 gas stations in that city.  So, if I take this as an average city I would say that there is one gas station per 2500 people.  There are 300 million people in the United States, so this yields around 120,000 gas stations.  That would have been my answer.

So, I just thought to check my number.  Turns out, this is suprisingly close.  According to the 2007 census (latest data available), there are exactly 118,756.  I would say that I nailed that. :-)