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[quote user="Khim"][quote user="Ken"][quote user="Undefined Reference"][quote user="KattMan"][quote user="Tom Dibble"]I mean seriously, flip a coin 5 times and get 5 tails, you next flip still has a 50% probability of either heads or tails, but the law of averages states it will probably be heads.[/quote]
Fortune cookie says you best to avoid casino in future.
Seriously, there is a reason casinos hand out cards for people to track which numbers have come up in roulette.
Independence means independence. Run a simulation if you doubt this fact.[/quote] Here are the specs for the simulation:
Simulate a coin flip a billion times. Find every sequence of five sequential tails and record the value of the next flip. Print a count of 6th-flip-heads and 6th-flip-tails.[/quote]
Sequence length from 2 to 10, guessing, on any occurring sequences of the same value, that the following value will be the opposite one:
I have to admit that this is sobering. The "law of averages" is a compelling fallacy. [/quote]
Check your conditions there. I think your statistics are a bit too consistently low. I would expect to see a couple more 50.001% in there. Although, it could be whatever random library you are using.
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As it is, I have the luxury of being able to decline job offers simply because I don't find them interesting. Since I have that luxury, I'm certainly going to use it.
Now, let's clear up this hat thing. The strategy is: if you see two hats of the same color, pick the third color, otherwise pass. I assert that these are the possible outcomes, and that all are equally likely: Alice wears blue, Bob wears blue, Carol wears blue: all say red (loss) Alice wears blue, Bob wears blue, Carol wears red: Alice passes, Bob passes, Carol says red (win) Alice wears blue, Bob wears red, Carol wears blue: Alice passes, Bob says red, Carol passes (win) Alice wears blue, Bob wears red, Carol wears red: Alice says blue, Bob passes, Carol passes (win) Alice wears red, Bob wears blue, Carol wears blue: Alice says red, Bob passes, Carol passes (win) Alice wears red, Bob wears blue, Carol wears red: Alice passes, Bob says blue, Carol passes (win) Alice wears red, Bob wears red, Carol wears blue: Alice passes, Bob passes, Carol says red (win) Alice wears red, Bob wears red, Carol wears red: all say blue (loss) If you believe there are other possible outcomes, or that any of these is not possible, or that these are not all equally likely, please clarify why.
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The law of averages itself is not a fallacy. Only applying it to predict the future.
Again, over time, you expect the series to average to the expected value of the distribution. This is because, in the future, you expect the average of the results to be the expected value of the distribution. The average of the prior series and the expected series is as close or closer to the expected value of the distribution than the average of the prior series itself.
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Well, that's my question then -- I don't think that problem really counts spotting a stupid trick. You have a statement known to be true "paid $30" and then a bunch of money shuffling that apparently ends in an inconsistent state. Can you find the step that created the inconsistent state, or prove that it isn't an inconsistent state?
Doesn't seem like a trick question to me.
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Your last 3 steps (labeled above) are wrong. Step 2, M gets annoyed by S since F is on the other side of river. Step 3, M kills S Step 4, F gets stranded on one side while M, D, G, and P move on. :)
The correct solution is:
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Manhole questions...
Ask who uses the manhole and what their concerns are:
Sewer worker would be concerned of not only safety (dropping inside), but also ease of access to the hole. So a question of diameter and area of the hole would matter.
Drivers (and by extension, the City) would want manholes that are least likely to wobble and are strong.
The City, who are paying for them would like ones that are cheap and also hard to steal.
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[quote user="OutsideInwards"][quote user="zip"]No, it is a trick question because it pretty much just amounts to making the person being asked look stupid for not knowing the answer (assuming s/he did not know already know the answer). Yes, this particular question is fairly easy to work out, but most people will find that their brain simply malfunctions when put into a position of answering a question like this when not expecting it. (Similar to people on game shows looking like freaking idiots when they can't answer the most simple of questions that even early elementary school children would know.)[/quote]Seems to me you just proved your opponents point, since all these puzzles are not used to find out your ability to solve complex problems on a spot, but rather to test your reaction to them and see your approach to solving them... Look, if you're being interviewed for a position that requires any customer interaction at all, how can the company be confident you won't call their customers stupid and storm out the room even if the customer IS STUPID? I can tell you that walking out of an interview does not help a bit. :))
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If the position being interviewed for is even remotely client-facing, the trait of having your brain "simply malfunction" when put in an "unexpected position" is not desirable.
I don't know what kind of position you were interviewing for, but if it's your opinion that "most people" will melt down when faced with this question doesn't that make it valid? I don't want to hire "most people."
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So basically you want your fellow programmers to negotiate with the exact same values that you use. Fair enough -- I think we'd all like to be part of a union that catered to exactly what we wanted.
It's just not going to happen, though.
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I strongly disagree with your assertion that everyone panics/brain farts/malfunctions when faced with trick questions or unexpected questions, especially in an interview.
Frankly I think it's less common than you think, especially among talented programmers. Not a 1:1 correlation, but still, I don't think good programmers melt down on math teasers as often as you're suggesting.
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"Course the person who answers that correctly probably just heard it before. Nobody thinks about weighing quarters that fast."
Funny you should say that, because I did think of exactly that divide-and-conquer approach.
I recently had an interview at a place where I really wanted to work, was willing to take a substantial pay cut to work there, and yet, the interview was "from hell" in some ways.
They asked me to describe how I'd move the mountain range on the North side of our town, to the South.
The dealbreaker, I think, was when I refused to talk about the Spring framework as a single entity (I consider it a bag of independent technologies), and when I insisted that AJAX was nothing but Javascript and XHR, nothing really special or magical about it. (If you know me, you realize I'm way qualified to speak on this subject.)
I don't think one of the people interviewing me liked my answers at all, and I ended up taking a totally different job, and never even called them back. Really strange too, because I was more than willing to start working for them right away, or at least I was, before that interview.
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"This means on several thousand spins of the wheel, you may see a few extra occurances of one number, and fewer of another. To take advantage of this you shouldn't bet on the unseen values, but rather on the values that occur most often."
To really take advantage of this, you should be the house and choose those locations for the 0 and 00.
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Your hypothesis was: "The result of a roulette spin depends on previous ones".
You executed a computer program which measures how much a spin depends on the previous ones, and found that amount to be "very close to none".
Your conclusion is that the hypothesis is false (and also that the measurement "very close to none" actually represents a true value of "none" with a small margin of error in the experiment).
Some people may ridicule that it took you a computer program to convince you of what is "obvious" (i.e. a roulette ball has no 'memory' as such). Ignore that criticism -- there's never anything wrong with testing out 'obvious' assumptions via an experiment; in fact doing exactly that has led to some important unexpected discoveries in the past!
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Depends. The way I understood it, he was only looking for single barbers.
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Say there is a guy who stands in front of two video game displays -- one of Mario Kart and one of Halo -- and he mutters "hate shooters" and starts playing Mario Kart. Is it sensible for the Halo players to shout "we beat you, you totally let us OWN YOU" at him? I mean, they CAN. But does it make sense to claim you beat someone who won't even engage in the game? I ask because it seems to be the same attitude that I see here. Some people are saying "won't play that game" and others are then shouting, "but then they totally BEAT YOU!!!"
No, they don't. The player has engaged in a game with a different group. He only cares about winning or losing in the game that he/she is actively participating in.
I think you are forgetting that we are no longer in the dot-com bust. I went out to interviews a month ago and in a week I had two competing offers. If I turn down one have I "lost?" It is no longer an employer's market. I wouldn't say it's an employee's market either, but it doesn't need to be. Once there are enough options, employees can choose rather than beg. And thus, this kind of "you should be grateful for the job" thinking will get repeatedly blindsided by people who say "going for a better offer, bye."It isn't a zero-sum game. It isn't all or nothing. Getting a job offer isn't difficult in the current climate, and turning it down isn't doom. Therefore, the employees on this forum who are weighing these jobs and rejecting unappealing ones do not strike me as idiots. They are simply doing the same thing the hiring manager is doing -- evaluating a fit. And their assessments are just as legitimate.
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Okay, one person on the bridge must have the flashlight whenever two people are crossing. It can be done in 10 minutes.
Give the flashlight to Mr 10-Minute, and have him start across. Now each of the other three can walk across in turn while Mr 10-Minute is crossing.
It doesn't say they have to walk at the same rate. :)
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Hmmm. Looks like this has higher than 75% chance of success. You get the job.
captcha: quake, in fear
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The correct maximum number of weighings is 3. Pseudocode follows: coins labeled: A,B,C,D,E,F,G,H bools ABCgreater, ADgreater if(A+B+C < D+E+F) { ABCgreater = false }else if(A+B+C > D+E+F) { ABCgreater = true }else if(A+B+C = D+E+F){ if (G=A) coin H is counterfeit else coin G is counterfeit } if (A+D < B+E) { ADgreater = false }else if{ ADgreater = false }else{ if(G=C) coin F is counterfeit else coin C is counterfeit } if (ABCgreater = ADgreater) { if (G=A) coin E is counterfeit else coin A is counterfeit } else { if (G=B) coin D is counterfeit else coin B is counterfeit }
Yup, you need to record information to do it. Those that required 4 are throwing away information that could reduce the number of weighings by 1. Average number of weighings is 2.75
CAPTCHA: poindexter
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This not only applies to teasers, some questions even from programming are ambiguous.
Amen!
I had an interviewer ask me what "immutable" meant. I hesitated for a second and asked "In what context?" and the interviewer launched into a very myopic explanation of the immutability of Java strings -- without even giving me a chance to answer the question. This was frustrating. If he had asked me to compare and contrast String with StringBuffer, and give examples of where each was appropriate and why, he would have gotten the information he was looking for and much more. Instead, I had to launch into a lengthy response to try to convince the guy that I actually DID know what he so patiently explained to me.
On another occasion, an interviewer asked me "What kind of tags would use in ASP?" I was pretty flabbergasted and said something like "Whatever tags you'd need to make the page..." He asked "Yes, buy what kind of tags would you use?" I said something like "Well, if I was generating an HTML page, I would start with <HTML>..." He looked at me like I was an idiot, and asked me what kind of tags I would use AGAIN. Finally, something clicked in my head and I said "Are you asking me if I know to use less than percent sign to separate the code from the markup?" And the interviewer smiled and moved on. He would have gleaned a whole lot more in less time by telling me to write an "Hello World" program in ASP on the greaseboard.
Another example of this kind of idiocy was an interviewer who asked me a question and decided that the only correct answer to the question was "Use a sniffer" and kept asking me the question until I gave him the "right" answer. Even though the first three answers I gave him were perfectly acceptable and two of them were simpler and provided better debugging information. Finally, I got angry at him and said "Okay, what do you want me to say? A sniffer? Is that the CORRECT answer?" and he got all excited and said "A sniffer" in a conspiratorial tone of voice and ended the interview.
The strangest thing is that of these three jobs, the last one, where I got pissed, is the job that I got an offer for, accepted, and it was the best place I ever worked.
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And you know what? Later, I went online and found the puzzle, and discovered that there are TWO correct possible answers, and I simply had given him the one that HE didn't have written down on his paper! I'm sorry, but that's asshole-ish in my mind. And what did this interviewer have to show for hiring puzzle geniuses? A god-awful Web site for a "Web 2.0" company that apparently hadn't heard of the XMLHttpRequest Object and appeared to be stuck on Web 1.0 beta (gray background, tables with thick beveled borders, animated GIFs). My desire to "bring them up to speed" diminished rapidly in the interview and finally when I realized he was stuck on getting exactly the answer he had written down in front of him, I just said, "No, I'm not retracing my steps, I need to go pick up my kids. Bye."
Did I lose the job? Did someone else out-compete me? So what? I'd rather walk and find a sane place to be.
That kind of crap only reaffirms why, when I have been a hiring manager, I stop any employee who tries to ask riddles in an interview. It is almost always the employees who are very geeky and lacking in social skills, and they almost always latch onto puzzles as "how to do awesome interviews with no prep." Thankfully, the HR team at my last job had my back, and would train employees in a host of other interview skills.
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Read the question more carefully. I can think of a strategy that yields a 75% chance of success. Not sure if you can do better, but you can definitely hit 75%.
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I thought everyone knew the joke about the whore, the two condoms and the three danish topologists
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You know what? Their risks are low enough already.
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Well, I missed a few pages of comments, but I think all the "right" answers I saw re: the 2 condoms / 3 women problem are all wrong.
Quoting, they are given:
A + B A A + InsideOut(B)
I take umbrage to this solution, since if I were in the position, I would want to avoid the double-layer encounter as much as possible, as it reduces the sensation to an unacceptable level. So I propose:
A B B + InsideOut(A)
I consider this to be the optimal solution.
captcha: muhahaha
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Some candidates are not even worth wasting time with an interview. Some people are not fit, and it's so obvious even before you start the interview with them. I tried highlighting the major problems that I see with candidates recently. Take a look: http://www.burag.com/?p=3
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Of course, you and both know we don't have STDs, so it's natural that we wouldn't consider that worry. ;)
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I'm not saying you don't have the right to act as you do - obviously you do. Just don't pretend it's anything other than a trade-off you're making; to claim that your choices are not choices, or that a compromised integrity is a sign of virtue, is an abrogation of the responsibility you take so seriously. Be conscious of what you hold dear, and of the compromises you make for its sake.
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