Critical Thinking Drills Influence Hiring Decisions

If you had to build a 150-story building, how would you go about doing it?

How many gas stations are there in the United States?

Why are manhole covers round?

How would you design a coffee machine for an automobile?

You’ve probably heard of some of these legendary interview questions asked at many high-tech companies — questions that baffle an interviewee as to how manhole covers possibly relate to a job as a developer, marketing manager, or a financial controller. On the surface, these seem like highly peculiar and illogical questions for an interviewer to be asking. It’s not necessarily the answer that the interviewer is looking for, but the thought process the interviewee uses to come up with the answer.

What is an interviewer looking for when asking how you would design a coffee machine for an automobile? When I do interviews I look for several things:

  • Creativity - What unique and innovative ideas you apply to a problem.
  • Critical thinking - How quickly you think on your feet and what assumptions you make to analyze problems and develop solution alternatives.
  • Grace under pressure - How you respond when put under pressure.

In one interview I conducted, the interviewee had a good resume and did great with answering technical questions. I was feeling pretty good about the interviewee and was leaning toward hiring him. Then I asked him how he would build a 150-story building. This is where things fell apart. He simply wasn’t able to show critical thinking or creativity in his thought process and stammered through an answer. I ended up declining the candidate because, while I thought he had the technical skills to do the job, he didn’t demonstrate some of the core attributes that my company looked for in its employees.

When you’re being interviewed, here are some techniques to keep in mind when faced with “manhole cover” questions:

  • Verbalize your thought process - These types of questions are meant to assess your thought process. Don’t be afraid to verbalize your thoughts so your interviewer can follow how you think through problems. You won’t get any points for working something out in your head and blurting out an answer.
  • Allow your creativity to show through – From my perspective, the more creative and innovative the thought process and answer, the more I am impressed with an interviewee. Don’t be afraid to color outside the lines on your answer.
  • Feel free to sketch something out - Don’t be afraid to step up to a whiteboard or pull out a sheet of paper and sketch something out. Again, how you think through problems is the most important thing to demonstrate, so if sketching something out helps your thought process, by all means do so.
  • Use assumptions to estimate your answer - Interviewers like to see how you use assumptions to estimate an answer. For instance, if answering the question of how many gas stations there are in the United States, using the number of people in the United States and making assumptions on number of people per gas station would be one means of estimating the number of gas stations.
  • Stay concise and avoid babbling – Verbalizing your thought process is good, but try to keep things concise and avoid babbling or random verbalizing. If you need to stop for a few seconds to collect your thoughts, do so.
  • Don’t panic – If you get one of these questions, don’t panic. Take a deep breath, think about it for a few seconds, and have fun with your answer. Yes, you’re being interviewed for a job that you’d really like, but in the big scheme of things it’s just a job. Keep calm and let your creative juices flow.
  • Don’t insult the interviewer – During one interview I asked an interviewee how he would go about testing a toaster. The interviewee asked what relevance the question had to the job and told me that it was a dumb question. The interviewee’s response told me everything I needed to know and made my hiring decision very easy. Insulting the interviewer will only demonstrate arrogance on your part. Don’t do it.

Expect that you’ll be asked oddball questions. Remember that they are intended to see how you think, how creative you are, and how you respond under pressure. Just stay calm, verbalize your thought process, show some creativity, and have fun with your answer. You’ll get your point across to your interviewer and will make a positive impression that can mean the difference between being hired and being passed over. Oh and for the answer to “Why are manhole covers round?”, it’s the only shape that won’t fall through the hole when tilted.