Answering 25 tough interview questions, part 3

No-one really seems to care about this series (seven comments on part 1, none at all on part 2) but I’m finding them a pleasant diversion so I am ploughing on anyway. Original questions from here.


11. “What have you done in the past to get out of a tricky situation?” – Asked at Virgin Atlantic Airways.

“The best defence against an atomic bomb is to not be there when it goes off” — attributed to the British Army Journal.

This is good advice for life, not just for bombs. On the whole, I avoid getting into tricky situations in the first place. How? By keeping things simple. I don’t tell lies, so I never have to get out of a tricky situation caused by a lie. If I find myself in an argument where I am not completely sure of my facts, I just back down.

Of course, sometimes tricky situations happen on their own — like a piece of software developing a mysterious bug just before an important demo. I don’t think there’s any trick to dealing with situations like that: all you can do is keep calm, think clearly, and do your best to figure out the problem.

12. “Why is 99% not good enough?” – Asked at Parcelforce Worldwide.

99% of what? Scoring 99% in an examination is outstanding. Eating 99% of a meal is nutritious. A football team winning 99% of available points is sensational. A space program that gets 99% of its payloads safely into orbit is doing pretty well. On the other hand, if 99% of your body is functioning correctly, you could be in serious trouble.

If 99% of the lines of code in your program are correct, you have bugs. Then again, if the bugs are in the 1% of the code that’s almost never used, maybe it actually doesn’t matter that much? (The idea of a bug-free program is an illusion: Firefox currently has more than 10,000 registered bugs.)

A much better question would be: when is 99% not good enough. It’s easy to trot out mantras like “we don’t accept anything less than perfection” without thinking about the trade-offs. The Firefox people can invest the next decade or six into fixing all those 10,000+ bugs; or they can develop the new features that people need. Perfection is often not only unattainable, but a distraction from the real issue.

13. “How many ways can you get a needle out of a haystack?” – Asked at Macquarie Bank.

A lot.

  • Burn the haystack. The needle will remain in the ashes.
  • Blow the haystack away. The needle will remain on the ground.
  • Drop the haystack in water. The needle will sink to the bottom.
  • Use a powerful magnet to pull the needle out of the haystack.
  • Allow cattle to eat the haystack. Extract needle from sick cow.

What these solutions have in mind is that they exploit a property that is different between the sought element and the substrate. #1 works because hay burns but steel doesn’t; #2 and #3 work because steel is denser than hay; #4 works because steel is magnetic and hay isn’t; #5 works because cow can digest hay but not steel. You could use other properties such as the needle’s ability to reflect X-rays.

14. “How would you explain Facebook to your Grandma?” – Asked at Huddle.

“Your friends write about their lives, and take photos. These things are available for you to read and comment on. You can also write and take photos, and make them available for your friends to read. If you like, you can make new friends.”

15. “If you entered into a room full of people with different interests, what would you do?” – Asked at Ernst & Young.

Depends on the situation, of course. If it’s a party, I’d find someone who shared an interest and talk to him or her. If it’s a working group, I’d wonder who had convened a group of people who were not interested in the problem we were working on. In general, people can sort themselves out pretty well, and don’t need any leadership in social situations. But in a work situation, when there is some specific thing that you’re trying to achieve, you just need to make it clear to the people why that thing is important.

16 responses to “Answering 25 tough interview questions, part 3

  1. I’m interested in these! Please keep going with them.

  2. First, I have to comment on that 99% question. I would find that question being asked a reason to get up and leave the interview. Any company who asks that question sounds like the kind of company that will ask someone to give 110% or other crap like that.

    My other comment is that the reason I’m not particularly interested in all these “gotcha” interview questions is that the sole purpose of a job interview should be for you, the potential employee, to explain to the company why hiring you will improve the company and make it more successful. Not a single one of these questions provides any insight into that topic and since that topic is the only thing that matters, these questions don’t really matter. They’re neat thought experiments, but if asked these questions by any company during an interview, your next question should be, “why am I wasting my time being here?”

    See this excellent blog on this subject:

    Although, I suppose if the company you’re interviewing with specializes in finding needles in a haystack, or I’d even go so far as to say sifting through materials to find other materials (ie. recycling) then the needle in a haystack question would be pertinent to the job.

  3. Thanks, Kyrall. I will probably finish the 25 if only for my own satisfaction.

    jwerpy, I agree that most of these questions are of limited value in assessing the likelihood that someone will perform well in a job. But that’s only one application of such questions, and not the one that interests me. I think of them more as mental stretching exercises, and as ways of finding out what I think by seeing what I say (as E. M. Forster had it).

  4. I agree it’s a fun series of posts, please continue them.

    Reading your response to #13, I realize that an accurate answer for me would be:

    “Me, personally, not very many, unless I was really motivated and even then I don’t know how good my odds of success would be. I can think of a number of strategies which might work, but the thing I learned from the lab science classes at university was that, even when I was completely solid on the theory, the labs did not always work out the way that they should have. Execution is tricky, and is a separate skill from design, and I do not trust my abilities to execute in getting a needle out of a haystack.”

    Incidentally, I think your answer of “Blow the haystack away” is one which probably wouldn’t work in practice.

  5. Blowing it away — depends on circumstances. If it’s in a sealed room and you can deploy fans to blow all the hay up in the air, I think it’s good.

  6. I’ve really been enjoying the posts too, and I’m planning to write my own version of the answers on my blog at some point (when I have more time).

    One comment on the 99% question: of the fifteen you’ve answered so far, I think this is the question most suited to the employer. If you’re talking about parcel delivery, then 99% isn’t good enough, because it would (quite rightly) diminish trust in the postal system. When I put a letter in a post box, or take a parcel to the post office, I expect it to arrive with dial-tone reliability. Losing 1% of parcels would be a cause for concern.

    I recognise that you’re answering the questions in the general sense, not just as if it were an interview, but I think the match between employer and question is somewhat interesting there.

  7. True, Alex, and a good point — I should have addressed (among the other examples) what 99% means for a parcel-delivery company.

  8. Mike,

    #11 is a “behavioral question.” Anybody being interviewed for a job needs to recognize these. The interviewer is asking you to remember an actual sticky situation you were in and describe in detail what you did to get out of it. The idea is to get past your philosophy because professed philosophy can so easily differ from how you actually act at work. It’s also just a way to get you to show an example of your thinking and working and interacting processes, and your ability to describe them, maybe a clue about how honest or evasive you are; although they want to see *how* you answer, they’re not necessarily looking for a *correct* answer.

    Of course, if your philosophy successfully steers you out of sticky situations it’s good to say that, too.

    For #12 I was tempted to give a long-winded version of jwerpy’s answer. I also didn’t notice that it was asked by a parcel company. So, I should think about who’s asking, if a question triggers my BS alarms and paranoia think again, and and if I’m unclear about the question (99% of *what*?), ask first. Asking clarifying questions is a good answer all by itself.

  9. Steve, I take your point on #11. But honestly, when I thought about this, I found it hard to remember a tricky situation I’ve been in. Since prevention is better than avoidance in most cases and it seems to be my natural mode anyway, I just answered honestly.

  10. Here are your results…..

    11) Pass (just about).
    12) Fail (didn’t give an answer to the question; as pointed out by other commenter, losing 1% of your parcels would be a real problem).
    13) Pass (lots of good solutions and a good understanding of the problem).
    14) Pass (clear concise answer).
    15) This is a genuinely stupid question.

    Keep up the good work. Carry on. :)

  11. Pingback: Answering 25 tough interview questions, part 4 | The Reinvigorated Programmer

  12. My initial reaction to the 99% question would probably be annoyance, and I may even fall into the trap of giving a potentially snarky response about how in many situations, 99% of a goal is exceptional.

    What the interviewer is really asking is something along the lines of, “Why is it not acceptable to not do your best work?” or even more directly, “If we hire you and assign you a task you’re not fond of, are you going to half-ass it?” This question is a question about attitude and work ethic, not percentages.

  13. You could be right, Bobwise; but even if so, the right answer is not to acquiesce to the completely unrealistic 100%-all-the-time goal. I will never dedicate 100% effort to a job, and neither will you. Especially if you’re ill, or your wife has recently lost her job, or your children are having problems at school, or noisy neighbours are preventing you from sleeping. The adult approach is to accept this and adjust expectations accordingly. Any employer that says it wants 100% is either being completely unrealistic or (more likely) hasn’t given any thought at all to what that actually means.

  14. Well said, Mike. If I were asked this question in an interview, I would probably ask for clarification (“Do you mean why is it unacceptable to not do my best possible work at all times?”) and then try to make a case why that is an unrealistic expectation.

  15. Pingback: Answering 25 tough interview questions, part 5 | The Reinvigorated Programmer

  16. So, facebook sounds a lot like group social anxiety disorder therapy. :/

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