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Job interview questions for Google
How many piano tuners are there in the entire world?
Or how about?:
You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving in 60 seconds. What do you do?
Here are many more, via Craig Newmark. I gave a talk at Google on Friday (soon coming on YouTube), and yes they really do have toy stations and Lego blocks for everyone. They also have the tastiest workplace cafeteria I've sampled. Everyone is smart and beautiful, and I didn't want to leave.
Posted by Tyler Cowen on September 17, 2007 at 07:30 AM in Web/Tech | Permalink
Comments
These questions are definitely not what Google asks for technical positions, at least not when I interviewed there. Most of them are standard management consulting questions. For a technical position, I got questions like: "How do you compute the nth digit of e without knowing digits 1..(n-1)?", and how to implement a tcp/ip header.
Posted by: DK at Sep 17, 2007 7:53:37 AM
You are shrunk to the height of a nickel and your mass is proportionally reduced so as to maintain your original density. You are then thrown into an empty glass blender. The blades will start moving in 60 seconds. What do you do?
The answer is you die immediately because you cannot scale biological systems proportionately. Even doing clever things like removing every second cell in a row will fail miserably.
Nitpicky? Maybe, but why would they say something technical like "your mass is proportionally reduced so as to maintain your original density" when the concept was completely ridiculous to begin with?
Posted by: Brandon Thomson at Sep 17, 2007 8:42:54 AM
You see this sort of nonsense anywhere there are far, far too many people applying for entry level
jobs. Was endemic to investment banks back in the Gordon Gekko days when I was involved in it, and
assume it's been robust since. Works best if you have two interviewers, one asking straight questions
and the other interrupting the answers with this stuff to see how well the candidate can get back to
the first answer.
I generally found whether or not the candidate had researched any sort of arcane topic you had no knowlege
of, and could explain it to you and get you to understand and buy off on their thesis in 10 minutes, was
the best determinant.
These - the first is just a straight "can you estimate" question and the second, just lie down and wrap
yourself around the (non-rotating) bushing, where the wind will be least.
Posted by: mkl at Sep 17, 2007 9:02:25 AM
I remember running into the first problem in a book on Microsoft interview questions, and being startled that the answer the book came up with was pretty drastically different than mine. (As I vaguely recall, my guess started from how many piano tuners I knew of, in various areas where the population was about 100,000, and working from there, whereas their method started with guessing how many pianos there were....)
Posted by: Sol at Sep 17, 2007 9:41:02 AM
On another note: Do you think Google checks the Google history of the job candidates? :)
Posted by: J at Sep 17, 2007 9:47:57 AM
9. Every man in a village of 100 married couples has cheated on his wife. Every wife in the village instantly knows when a man other than her husband has cheated, but does not know when her own husband has. The village has a law that does not allow for adultery. Any wife who can prove that her husband is unfaithful must kill him that very day. The women of the village would never disobey this law. One day, the queen of the village visits and announces that at least one husband has been unfaithful. What happens?
--
I remember this from game theory. Immediately, every woman kills their husband. But now I'm having trouble remember why this is the case. It has to do with private vs. public knowledge, but I'm drawing a blank (I sucked at game theory).
Posted by: jason voorhees at Sep 17, 2007 9:50:49 AM
The first question is a so called Fermi question (a physicist famous for his ability to estimate).
http://en.wikipedia.org/wiki/Fermi_question
Posted by: ringemann at Sep 17, 2007 10:09:32 AM
Why would you want to work at Google anyway? It's completely setup like a college campus, and because of that they get tons of hyper-intelligent grads who don't have to continue doing anything for themselves - just suckle on the teat that is Google. They supply in house everything, and will ensure you get there. Just like a college, it's designed so you don't need to leave - hoping you won't. So screwwwww that!
Posted by: Jeremy at Sep 17, 2007 10:25:31 AM
Jason, as I've seen that problem started, there is a time component as well:
http://www.math.temple.edu/~paulos/parable.html
Posted by: Sol at Sep 17, 2007 11:11:29 AM
Jason -- it's easy to see why if there are only 2 married couples.
If one woman didn't know of any cheaters before the queen came, she would immediately kill her husband upon hearing the annoucement. If no one gets killed right after the announcement, it means that both women were aware of cheaters which means that the men get killed a little bit later.
If there are 3 couples, then from each woman's point of view it's possible that each of the other women sees only 1 cheater. But women who only see 1 cheater would expect the cheater to be killed immediately after the queen's annoucement -- unless their husbands had also cheated! So these women would murder their husbands a little bit after the announcement. When this doesn't happen, it means that everyone sees 2 cheaters, which means everyone has cheated, which means the men get murdered at this point.
Haha, that's not very clear, is it? But that's the idea.
Posted by: LN at Sep 17, 2007 11:34:46 AM
[Immediately, every woman kills their husband]
no, the slaughter happens after 100 days, as each wife waits for the others to kill their husband (because she assumes that they all know that hers was faithful) and then realises that they haven't because they didn't because he wasn't.
Posted by: dsquared at Sep 17, 2007 11:51:22 AM
If the adultery has occurred prior to the queen's arrival, then every wife knows that every other wife is already unaware of their husband's adultery. When the queen announces that at least one man is guilty, why would any wife expect any of the 99 husbands to be killed- she already knows that the other wives don't know because they had not enforced the law up to that point. In other words, the queen has added no knowledge that wasn't already known prior to her arrival.
Either that, or I will never work at Google.
Posted by: Yancey Ward at Sep 17, 2007 12:24:39 PM
I haven't interviewed at Google (nor do I plan on doing so) but the type of interview questions really depends on what position you are going after. So I always think its a bit silly when this type of topic comes up. Go back 5 (or 10) years and you will see the exact same type of issue around microsoft interview questions (e.g. the now infamous manhole cover question).
Posted by: yoshi at Sep 17, 2007 12:39:36 PM
Um, I don't see how the queen's pronouncement affects any of the wives. It's stated:
(a) Every man in a village of 100 married couples has cheated on his wife, and
(b) Every wife in the village instantly knows when a man other than her husband has cheated.
So every wife in the village was aware of 99 cheating husbands prior to the queen stopping by. The
men are only in trouble if two wives each state they are aware of 99 other cheaters.
Re Google's hiring practices, I think the comment that everyone is smart and beautiful is pretty
dispositive, and not in a good way for shareholders over the long term.
Posted by: mkl at Sep 17, 2007 12:47:58 PM
Well, if they are all pretty, then I clearly don't have to waste my time sending them my resume.
Posted by: Yancey Ward at Sep 17, 2007 12:56:01 PM
it looks to me as most of these questions are examples of the well known Fermi problem. See:
http://en.wikipedia.org/wiki/Fermi_problem
Posted by: Jean-Christophe at Sep 17, 2007 12:59:44 PM
The queen is a bit of a distraction. If everyone becomes aware of 99 cheaters at the same time, that's when the clock starts ticking.
Posted by: LN at Sep 17, 2007 1:02:16 PM
As for the blender question, I would probably crap my pants just before dying a horrid death. However, one could possibly relocate to the axis of the blades and hold on, though you would probably pass out due to the equilibrium disorientation. In addition, one could jump out over the spinning blades to catch the updraft, and out of the blender. Just some ideas.
Posted by: Yancey Ward at Sep 17, 2007 1:03:33 PM
LN,
As long as the women don't share information, then the clock is stopped, it seems to me.
mkl,
I think you are correct.
And, if it could be proven that a man is guilty, then why would any man stick around. Or is this one of those PC questions that has the explicit assumption that men are a bunch of Homers.
Posted by: Yancey Ward at Sep 17, 2007 1:13:32 PM
The link I posted earlier has a nice proof by induction of the why there is mass murder at day N = number of husbands. But I'm with Yancey and mkl -- I don't see how the queen adds any additional information to the system. Not only does every single wife already know that there is an adulterous husband, every wife knows that every other wife knows that.
Posted by: Sol at Sep 17, 2007 1:20:44 PM
All husbands should be saved according to the principle of cooperation in a repeated game!
I am already flat. No blade can cut me after I am flattered like a nickel!
Posted by: dog at Sep 17, 2007 1:45:13 PM
These are all old. I think these same problems were originally written about as "The Microsoft Interview", and I'm sure in 10 years they will be written about again as "The Interview"
Posted by: Rob at Sep 17, 2007 2:01:17 PM
Yancey,
Actually, I take it back, the queen does add information.
Go back to the 3-person case. Everyone knows that there are at least 2 cheaters, so it seems that the queen adds no information. But if your husband isn't cheating, that means that other women would see only 1 cheater. A woman who sees only 1 cheater assumes that the cheater's wife might not know if there are any cheaters at all. So the queen's announcement does carry some information in this case.
In the 4-person case, everyone sees 3 cheaters, and so they all know that everyone else sees at least 2 cheaters, and once again it's unclear what the queen adds. But... if a woman sees 2 cheaters, then she might think that these cheater's wives see only 1 cheater... and that the cheater's wife might not know if there are any cheaters at all.
Improbably, if there are 100 women, then you know everyone sees at least 98 cheaters. But other people might not know this; they might think that some women see only 97 cheaters. And women who see only 97 cheaters might think that other women see only 96 cheaters, and so on...
So the queen is actually crucial!
Posted by: LN at Sep 17, 2007 2:11:29 PM
The paradox seems to be that everyone already knows that everyone knows that there is at least 1 cheater -- so what could the queen add?
The answer seems to be that until the queen makes her announcement, it is not true that everyone knows that everyone knows that everyone knows that everyone knows... etc. etc. ... that there is at least 1 cheater.
You actually need the 100 iterations for the mathematical logic to kick in and prove that your husband is a cheater. I confess I find this pretty incomprehensible for N=100, but at N=3 or 4 it seems intelligible.
Posted by: LN at Sep 17, 2007 2:36:44 PM
Game theory is the answer to every one of these questions.
Not John von Neumann's game theory.
But the "what game are you playing?" theory.
Because its all a game.
None of these questions will improve hiring.
John
SIMCGLACC
(Sitting in my chair grinning like a Cheshire cat.)
Posted by: Shakespeare's Fool at Sep 17, 2007 3:26:51 PM
