Today I had an interview with a gentleman who asked me to determine how many veterinarians are in the city of Atlanta. The interview was for an entry-level development position.
Assumptions: 1,000,000 people in Atlanta, 500,000 pets in Atlanta. The actual data is irrelevant.
Other than that there were no specifics. He asked me to find this data using only a whiteboard. There was no code required; it was simply a question to determine how well I could “reason” the problem. He said there was no right or wrong answer, and that I should work from the ground up.
After several answers, one of which was ~1,000 veterinarians in Atlanta, he told me he was going to ask other questions and I got the impression I had missed the point entirely.
I tried to work from the assumption that each vet could maybe see five animals a day, in a total of 24 working days per month.
Using those assumptions, I finally calculated (24 * 5) * 12 = 1,440 pets/year, and with 500,000 pets that would come to 500,000 / 1,440 ~= 348 veterinarians.
What steps could I have taken to approach this problem differently, in case I run into this sort of problems in future interviews?
I agree with your approach. The average pet sees a veterinarian so many times a year. The average veterinarian sees so many pets per week. Crunch those numbers and you have your answer.
Just guessing off the top of my head, I would say the average pet sees a veterinarian twice each year. So that’s 1,000,000 visits. I’d say the average vet works 48 weeks a year, sees about a pet every 40 minutes, and works 30 hours per working week. That’s about 2,160 vists per vet.
1,000,000 / 2,160 ~= 462.
My answer is close enough to yours, given that the numbers are all guesses.