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Types of Interview Questions – Logic Questions

Posted by James M on November 23, 2008

Microsoft made logic questions famous in the 1990’s and early 2000’s and many other companies have since adopted them, although their use has declined slightly in recent years.  This brand of question is generally reserved for engineers, although it is not unheard of for it to be included in interviews of applicants for other types of positions.

Two of the most famous logic questions are:

  • Why is a manhole cover round?
  • How would you build an alarm clock for deaf people?

There are many variations of logic questions and entire books and websites have been dedicated to tackling them.  In this post I’ll give you two examples of how you might answer this sort of question.

One of the best sites I’ve found for lots of examples of this question type, as well forums discussing the answer, can be found here.

After reading this post you may want to consider reading the “sister” post about guesstimation interview questions.  This branch includes such famous stumpers as “How much does Mount Kilimanjaro weight?”  To read this post now click here.

Please note that these are not trivia questions—that is you are not expected to actually know how much Mount Kilimanjaro weighs for example.  The important skill to demonstrate while answering is your train of thought and the logical steps you mentally go through.  Unlike behavioral questions where you can take a minute to compose yourself before you answer, it is essential that you begin sharing your thoughts out loud immediately after you hear the question even if you are just in the process of wrapping your head around the problem.

I think this is best shown by example, so allow me to do my best.  I’ll write this in a free flowing casual style with minimal attempt to use exact grammar.  The goal is to replicate a process similar to what you would probably end up saying if you were in an interview:

How would you build an alarm clock for deaf people?

“Hmmm, let’s see.  If you have to wake a deaf person up obviously a sound would do no good.  So what are some ways I normally get woken up that aren’t sound?  Um…I guess you could have an alarm clock that pokes a person, but that is difficult to implement.  One time I got woken up by having water dumped on me so you could spray some sort of liquid on them, but that gets messy.  But on the other hand it might work, let me write it down and maybe come back to it later.

I remember when I was a kid I had a bed pad that gave me a small shock if I wet the bed so maybe something like that would work.  Like a pad of some kind, but shocking someone might suck.  But I’ll write it down anyway as an option.  What else could a bed pad do?  Let’s see…oh it could like vibrate maybe.  Actually, I have seen beds that vibrate in movies.  Yea, it might be good to have some sort of bed that shakes, but now that I think about it that is expensive and limits the type of bed one could have.  Ok, so back to the bed pad idea, only instead of shocking, it would vibrate.  It would lay on top of the bed but underneath the sheets.  It could vibrate when the alarm goes off and this would wake up the deaf person.  But I guess it would still be useful to have a bedside type clock that they can look at during normal circumstances to view the time, or if they have guests over.  So the vibrating bed pad and bedside clock could be one unit and be attached by a chord.  But that might be annoying and dangerous if there is a chord that you could trip over.  Um…maybe the bed pad and clock unit could actually be separate but communicate wirelessly.  So the bed pad would have a small receiver in it, and when the clock unit alarm goes off, it can send a signal to the bed pad and tell it to vibrate.

So I think that would be the final design.  A bedside clock that functions very similar to a traditional bedside clock, with the added feature that it can send a wireless signal to a bed pad that would then vibrate to wake the subject up.”

Analysis:
So as you can see the answer is a very free flowing thought process type response.  First, I went through an initial description of the problem in my head—alarm clocks use noise as a wake-up mechanism, but if you are deaf this wouldn’t help you wake up.  Second, I started brain storming ways you might wake someone up based on my own experience of getting woken up.  It is key to use some reference points for the assumptions, estimations, and solutions you create.  If you have a eureka moment in an interview and come up with an answer it will do you no good since the interviewer won’t be able to evaluate the thought process you used to create the solution.  That’s why it is so important to talk out loud and use your own experience to formulate a solution as you work through the problem.  Third, I talked my final bed pad solution out, thinking about what would and wouldn’t work and why that was the case.

Again, there really is no “right” answer to this type of question.  Maybe you want to have the deaf person wear an electronic bracelet that emits a small electrical shock to wake them up, maybe you want them to wear a watch that vibrates, maybe you want to spray them with a small mist of water, maybe shine a very bright light on their face—there are a million different answers.  The important thing is to find something that makes sense to you, after all it is you and your ideas that are being interviewed.

If you have any questions about this post or need any other guidance in your job search, feel free to e-mail me at: collegegraduatejobs@gmail.com.

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One Response to “Types of Interview Questions – Logic Questions”

  1. Fred said

    The fastest way to an alarm clock for deaf people is http://www.hammacher.com:

    The Sensory Assault Alarm Clock
    http://www.hammacher.com/publish/72516.asp

    maybe even
    The Tantrum Throwing Alarm Clock.
    http://www.hammacher.com/publish/75884.asp

    As for me, I’ll take
    The Peaceful Progression Wake Up Clock.
    http://www.hammacher.com/publish/70460.asp

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