Just say No to brainteaser questions at interviews

Since i'm a contractor i get interviewed a lot, i sometimes come up against these brainteasers which i usually dont mind. Sometimes they're good questions like how would i solve problem X using X language, because thats relevant, i think its a good question.<p>However, i hate when i get questions like "how many golf balls can you get in a double decker bus" and "whats your most embarrassing moment", both of these were questions i was actually asked in an interview. My answer to the first was "I dont know and i'm not going to try and work it out because 1) i dont have enough information and 2) its not relevant to this position. I'd happily answer hypothetical questions about situations that could plausibly come up during this position, but working out number of golf balls in a bus doesnt show you how i would solve the problem of the database running slow or validation checks not working correctly." For the second one i simply answered "I have never been embarrassed in a professional setting as i mainly just do my job and i'm not embarrassed to say 'I dont know' or to ask for help. The only times i've been embarrassed were in my personal life and those are stories not appropriate for an interview."<p>Needless to say, these were questions asked by the CEO of a startup i thought was absolutely amazing, i had sat through a tech interview with the CTO before the CEO came in and felt i did well with the tech questions. Once the CEO came in and asked me these questions, i wondered how an awesome startup was achieving this success behind the leadership of total and utter moron. I decided not to work there as i lost all respect for the CEO.

A few years ago I was interviewed by Microsoft in Salt Lake City, now closed. The job was a creative type job, a game designer. A fellow there said he was a tough interviewer. He ONLY asked me brain teaser type questions. His first question concerned a radio design 20 years from now. I drew what I thought it might look like and he seemed unimpressed with my answer.<p>He then asked me this: "You and your family of 9 are on one side of the river, there's a flash flood coming. There is a boat but it only holds 3 people. What do you do?"<p>I said: "I get in the bow, row to the other side, and wave 'good luck' to my family. See, I don't get along with my family very well."<p>He got a little agitated, and told me that in this case I love my family and want to save them. He asked me to try again.<p>I said: "I flip the boat over to make it more buoyant, put the kids on top and the adults hang on the sides."<p>He became angry: "There are piranhas in the river so you can't tough the water. Try again."<p>I said: "I lay the oars of the boat so that more people can ride in the boat..." He interrupted me by saying: "Just answer the question."<p>I said: "I have given you 3 creative and interesting answers. Since you are NOT trained in psychology you don't have any way of understanding my answers you feel frustrated."<p>He said: "This interview is over"<p>I said: "OK, but you know nothing about me".<p>I have refused to answer these types of questions since then.

I've had a few of these in my time, and I think, to an extent, they're legit, and I'll explain why.<p>I was asked once - "how many gas pumps are in Raleigh?". I asked back "do you mean pumps for the general public, or do we need to include commercial/industrial pumps too?" and "do you actually mean Raleigh proper or the metro Raleigh area? if so, how do we define that? All of the county?"<p>Next question was "go to the whiteboard and design a house". I took out the marker, started to draw, then turned and asked "who will be living there? Is this a single family or duplex? mobile home? stick built or modular?" and a couple other questions.<p>I was told I was the first people to ask questions before drawing.<p>I take the point of the brainteaser-type questions to be "how do you react to issues that come up where you don't know a lot of stuff?". For <i>some</i> positions, this is less important, but if you're a customer-facing position - even in development, you may interact with customers or other business units - how do you react when you get odd-ball "left field"-type questions? Do you keep your cool? Do you just react and say "that's stupid!"? Do you walk out in protest? Do you probe for more detailed information before making a pronouncement?<p>More than ever, I think 'brainteaser' questions are far more about personality-judging than intellect or even raw "problem solving" ability.

Ahhh, I failed (flailed) one of these once! I spent minutes trying to figure out "You have a business card in Japanese, how do you figure out what it says?"<p>I asked if it had the phone number, they said yes, and I said the numbers are the same as in English... They said "okay, what next?" ... I was stuck. Next? Well, I suppose I could take a photo of it and ask for someone to translate it online... Or find someone in real life to translate it for me...<p>After a couple of minutes, they were ready to move on, disappointed, when I said "Well, short of asking for help, or Googling the phone number, I have no idea off hand how to find it."<p>"Oh, well, searching the number, that's what we thought you were going for initially."<p>It was. I'd thought they meant "next" as in "other than that method". Having the number was so evidently "problem solved" for me, that I didn't explicitly say "search out online". ... I suddenly felt like I was in grade school again, and my teacher had failed me for not showing the work in math class. I had the right answer, but would never get credit. I went on to flop the next question or two, as I vaguely recall.

From the article: "I'm going to ask you to solve one of my problems for every problem you ask me. Remember, an interview is a two-way process, I'm trying to determine if I want to work with you too."<p>This is the best part really.. Instead of "just say no" remember it's a dialog. If the brainteaser is interesting or you can quickly respond to how you would approach solving it then don't be an jerk about it. And feel free to have a dialog ask something back and see how they approach problem solving etc. Make it fun and interesting for all involved. If you're going to work with these people you might as well start right now in the interview!<p>I never take an interview with a potential client or employer without having a very clear set of my own questions for them and getting those answered.<p>I often ask off the wall questions or talk about a deep problem we solved recently and ask for the candidate for ideas on how they would approach the problem. I always share the answer we came up with. The reason for the question is not a perfect answer but to see how a candidate approaches potentially solving the question.

Just say no to interviews. (Seriously. If a decision maker wants you hired nothing resembling one takes place.)

Here is something that I always wanted to do, but haven't had the nerve. At the end of the interview, when you are asked "Do you have any questions?", I'd like to say: "Yes. There are 5 sailors marooned on a desert island, and they collect all the coconuts (.....). So what is the number of coconuts?"

I'm not fond of brain teasers either, but small, self-contained questions have value. Often if they're simple enough you can use them in many interviews and establish a base line (if the candidate did a, b or c she will usually work out, if she took route d, that betrays a weakness in X etc).<p>This is not a replacement for evaluation of a candidate on their own merits, and having a good in-depth technical conversation. But I like having something to ground my evaluations in as well and make them even slightly comparable.<p>For reference, I do the same thing when I get interviewed; I have a few questions I ask any prospective company so I have some comparative way to evaluate them. Never bad to try to have <i>some</i> metrics in your process.

The most important point in this post is this: "an interview is a two-way process".<p>I am constantly surprised how many people come out of interviews without asking detailed questions about the company, job, culture and work atmosphere.<p>You have to be more sure that that they will be a good fit for you than you have to be for them. You will be one of many: they will be everything to you, probably for years.

I'm going to take the contrarian point of view here: partially for the sport of it, and partially because I genuinely think there's value in puzzles and brainteasers -- though I <i>do</i> think the value is limited, circumstantial, and merely one datum out of many in an interview.<p>These questions are about having a logical process, regardless of where it gets you, and spelling that process out in a sequential fashion. It's more important to communicate "I do X, and check for Y. Then I do Y, and check for Z" than it is to arrive at a reasonably accurate Z. The added component of pressure (i.e., you've only got a few minutes, in the uncomfortable setting of an interview, in which to answer the question) helps (or allegedly helps) detect your ability to remain calm and logical under tight deadlines.<p>Basically, the question is asking "Under pressure, and faced with a seemingly insurmountable problem, will this candidate give up, or will he try to address obstacles in a rational, collected, and systemized fashion?" They're essentially variants on the Kobayashi-Maru test of Star Trek fame.<p>Furthermore, I don't agree with the apparent consensus that oddball "puzzle" questions would be better replaced with more technically relevant brainteasers. That's not the point. You have technical questions to test your technical literacy. These questions are trying to test your character. (Brainteasers are often non-technical precisely because the interviewer doesn't want you to be able to fall back on existing knowledge as an escape hatch from the question). Some brainteaser/puzzle questions are much more inane than others, but the exercise itself isn't entirely worthless.<p>I have never asked a puzzle question in an interview. If I were compelled to do so, I would never hire someone purely on the basis of his or her performance on one. It's one of the least important variables in a hiring process. But I'd consider with some skepticism anyone who outright refuses to answer a brainteaser, or who gets totally flummoxed by one, or who gives up without at least attempting to work out an approach.<p>Ultimately, no single type of interview question is flawless. That's why you have a wide variety in your arsenal. You've got technical questions, case questions, puzzle questions, whiteboard questions, and even the oft-derided "Tell me about a time when..." questions. In isolation, none of these types is sufficient. In combination, they test different aspects of a candidate's thought process and preparation.

The main problem I have, is when I've seen the answer to a question but don't remember it 100%. Your brain generally goes into recall mode, and rather than actually solving the problem I sometimes give an inaccurate answer and it can become hard to kick your brain back into thinking the answer through. Sometimes telling the interviewer you've heard the question before is enough to make him move on, other times they want to hear your answer anyway.

The review article "The Validity and Utility of Selection Models in Personnel Psychology: Practical and Theoretical Implications of 85 Years of Research Findings"<p><a href="http://mavweb.mnsu.edu/howard/Schmidt%20and%20Hunter%201998%20Validity%20and%20Utility%20Psychological%20Bulletin.pdf" rel="nofollow">http://mavweb.mnsu.edu/howard/Schmidt%20and%20Hunter%201998%...</a><p>sums up, current to 1998, much of the HUGE peer-reviewed professional literature on the industrial and organizational psychology devoted to business hiring practices. There are many kinds of hiring screens, such as resume reviews for job experience, telephone interviews, in-person interviews, checks for academic credentials, and so on. There is much published study research on how job applicants perform after they are hired in a wide variety of occupations.<p>The overall summary of the industrial psychology research in reliable secondary sources is that two kinds of job screening procedures work reasonably well (but only about at the 0.5 level, standing alone). One is a general cognitive ability test (an IQ-like test, such as the Wonderlic personnel screening test). Another is a work-sample test, where the applicant does an actual task or group of tasks like what the applicant will do on the job if hired. Each of these kinds of tests has about the same validity in screening applicants for jobs, with the general cognitive ability test better predicting success for applicants who will be trained into a new job. Neither is perfect (both operate at about 0.5 level in validation studies), but both are better than anything else that has been tested in rigorous research, across a wide variety of occupations. So if you are hiring for your company, it's a good idea to think about how to build a work-sample test into all of your hiring processes.<p>For legal reasons in the United States (the same consideration does not apply in other countries), it is difficult to give job applicants a straight-up IQ test (as was commonplace in my parents' generation) as a routine part of a hiring process. The Griggs v. Duke Power, 401 U.S. 424 (1971) case in the United States Supreme Court<p><a href="http://scholar.google.com/scholar_case?case=8655598674229196978&#38;q=Griggs+Duke+Power&#38;hl=en&#38;as_sdt=2,24" rel="nofollow">http://scholar.google.com/scholar_case?case=8655598674229196...</a><p>held that cognitive ability tests used in hiring that could have a "disparate impact" on applicants of some protected classes must "bear a demonstrable relationship to successful performance of the jobs for which it was used." In other words, a company that wants to use a test like the Wonderlic, or like the SAT, or like the current WAIS or Stanford-Binet IQ tests, in a hiring process had best conduct a specific validation study of the test related to performance on the job in question. Some companies do the validation study, and use IQ-like tests in hiring. Other companies use IQ-like tests in hiring and hope that no one sues (which is not what I would advise any company). Note that a brain-teaser-type test used in a hiring process might be illegal if it can be shown to have disparate impact on some job applicants and is not supported by a validation study demonstrating that the test is related to successful performance on the job. Companies outside the United States are regulated by different laws.

A contrarian p.o.v: They are going to lose out on exceptional cases where the candidate is a great engineer but is not able to devise a strategy towards a solution. However, there is a huge correlation between a good engineer and the ability to arrive at the solution (keep in mind they look at how you arrive at the solution too)<p>Personally, I'd make the candidate solve a decent intermediate level problem using a computer (and Google too). Give him/her the closest approximation of the typical job environment.

I was once asked to solve the monty hall problem a couple days after I saw the movie "21"

Crikey, you really think that attitude flies in interviews?

Not everyone who asks these problems is an idiot. Given the amount of dick-swinging that goes on from Google employees and the famed interviews one gets from the big tech companies I can imagine a lot of younger managers reading these and thinking that it's how you get hold of great engineers. The simple fact is that a lot of the time interviewers aren't experienced at interviewing, and most of them will spend longer formulating a process than an interviewee will spend preparing for said interview.<p>Anyway, surely the ideal thing to do would be to play along with the interview, answer the stupid question as best as you can and when the interviewer ends with "any questions for us?" you ask them why the felt it was necessary to test you on a general-purpose brainteaser with no relevance to the job when they could have asked something more relevant, like "x". This way you show that you roughly know what you're doing, you're aware of how the interview went and you've provided a question that will make people sit up and think.

This is very true. How to get past first interview, without ever knowing what you are talking about: Take 15 interviews where you fail miserably, record them all - at some point you have a pool of questions/answers that are good enough to get past the first interview.

If anyone refused to answer questions like this in an interview I was running, I would ask them to leave and tell them they wouldn't be hearing from us. I don't care what your qualifications are, if you are an asshole who will not take directions, then I don't want you in my department.

"How much would you charge to naturally irrigate the sahara desert"?<p>"How many golf balls can you fit in a bus"<p>"How many piano tuners could be employed in Seattle?<p>These questions do have everything to do with a programming job, it tests your ability to take an abstract problem and break it down logically into reasonable parts. It's called a Fermi problem and if you are incapable of thinking through them, I don't want to work with you.<p><a href="http://en.wikipedia.org/wiki/Fermi_problem" rel="nofollow">http://en.wikipedia.org/wiki/Fermi_problem</a>