Interview questions

Got an interesting one today, and I’m curious what solutions people can come up with. The interviewer insisted “there’s a lot”, but I’ll be damned if I can think of more than one.

You have an 8-gallon cylinder, with a line on the side marking off the 2 gallon point. How can you use this cylinder to measure 1, 2, 3, 4, 5, 6, 7, and 8 gallons of water? Yes, there’s only one cylinder (shaped liked an oil drum).

Highlight to see my answer: [color=#EFEFEF]You can tilt the cylinder where one corner of the water level is at the bottom, and one corner is at the top. This bisects the height & width plane of the container, so you know that it’s half full; the amount of water in the container is 4 gallons. You can use the same method with the 2 gallon mark to get 1 and 7, and treat the 2 gallon mark as a 6 gallon mark for 3 & 5.[/color]

When you say cylinder, what do you mean?

8 gallons is a gimme. So is 2. If this is a container that can be inverted then 6 is easy too. Inverted you can fill it to the 6 gallon point, flip it and pour it out til you’re down to the 2 gallon mark and what you poured out would be 4 gallons.

Are you sure there isn’t a second container? I remember being asked a bunch of these kind of questions in like the 1st or 2nd grade when I was being scouted for the Talented and Gifted program, but usually there were two containers of different measure.

So, I’ve got all the evens figured out. To get the odds I’d need to put a divider down the center of the cylinder and repeat the same methods as above, but with the results halved. Based on the vagueness of the question, I’ll assume that’s within the bounds of what is acceptable.

I will use the cylinder to go to the store and carry home better measuring devices.

I agree – with one canisters, there’s nothing that can be done unless you tip and do other things that you’re never allowed to do.

You need something with an odd number somewhere in the mix.

I can’t see any more solutions that only involve one drum.

Really though, even without the 2 gallon mark, it would be easy to divide the cylinder into 8 parts and put down marks for all the quantities as long as you had a pen or something. It’s not difficult to divide things in half – you can use your arm/body as a measuring stick if need be.

Well, they did specify that guesstimating like that wasn’t acceptable. It makes sense; the answer would be far more inaccurate that way than by the tilt/half method.

The tilting/half was acceptable, by the way. I just can’t see any others.

As long as you have something which doesn’t change in length, you can find the half-way point about as exactly you want – as exactly as a ruler anyway.

Jason’s answer is pretty good; I was thinking of something similar but hadn’t thought of quite like that. That seems to be the best method.

— Alan

Oh, I only got that one after a bit of prompting from the interviewer. Not all too impressive a performance, but fuck it, you can’t do insight on command.

What sort of job involves you screwing around with a measuring cylinder? I thought you were better qualified.

This from a man who can’t even tell us how to use an 8-gallon cylinder to measure out 1, 2, 3, 4, 5, 6, 7 and 8 gallons of water…

Microsoft interview, of course. They’re really cutting down on the puzzles, though.

I think the way you did the “Highlight to see my answer” thing was more cool / insightful than the answer itself. Well, not really, but it was pretty neat. 8)

color=EFEFEF !

Don’t get me started on these types of questions.

I walked out of an interview that consisted almost completely of a dipshit that obviously hadn’t showered in days trying to get me to think of silly ways to determine the probability of red and blue marbles flying out of my ass or something.

These questions serve one purpose:

They make the interviewer feel smug, they generally make the interviewee feel stupid, and they mask all the real issues involved in hiring people.

I’ve gotten into long debates about this, and the stock answer from the retards that think these questions are helpful is that these types of questions demonstrate “how fast you can think” or “your ability to really use your brain” or some such crap.

I’ve had a number of different jobs in the IT industry, and NONE of them ever involved anything even remotely like coming up with a trick answer to a trick question. Nobody ever fucking saves the day in a MacGuyver like fashion with duck tape and 8 gallon cylinders that only have one fucking mark on them.

I think that this whole fucking question thing is a huge embarrasment to the industry. It just demonstrates what a bunch of arrogant pricks we are and the lengths we’re willing to go to demonstrate that we’re smarter than all the other assholes who just don’t get computers.

Meanwhile, the number one supporter of wankoff questions like this, Microsoft, is producing shit operating systems that piss people off like mad.

Meanwhile, Steve Jobs has basically oscillated back and forth between being a visionary and an interior fucking decorator.

There are entire corporations out there who’s IT infrastructure is a steaming pile of shit because programmers are too busy screwing around with whiz-bang crap and not busy enough with ensuring that things just work.

If I could instantly get rid of one stupid asstastic trend in this screwed up and whacked out industry, it would be these fucking questions.

So in other words, you’re saying you don’t know the answer, Mr. SpoofyChop?


Scary to say, but I’m with Spoofychop.

And I’m good at those sort of things.

But hey, did anyone read the book about these tests?

I think the puzzle questions are kind of dumb, as they’re an extremely blunt force instrument to determine whether you have a problem solving mentality or not. Much better to just have a programmer run through a skeleton of a design. Puzzles of this type map to various design problems in interesting ways, but fuck it, just ask the design problem.

I read that book; it’s interesting (and the “these are IQ tests by a different name” angle is extremely so).

Mind you, I’m obscenely good at these things, so I guess that gives my opinion extra force or something.

This is probably the second worst thing about these questions. The very first thing you hear if you suggest you think they’re stupid is “Oh, it’s probably because you’re not able to figure them out! Winking smiley face!”

I was in all the “gifted” programs when I was in school. In college, I spent four years getting a degree in Physics and Computer Science. During these years, I spent a hell of a lot of time solving trick problems with fancy pants bullshit solutions. Now I spend my days attempting to design and write complex software systems.

And you know what? In my entire time working in the real world, I never once used a fancy bullshit solution that I had to quick come up with in 60 seconds. Never.

Look, there are obviously a lot of people around here that are “smarter” than me and that are more “accomplished” than I am. That’s great…some of these people are making the awesome games that I love!

But I really wonder at the reasons why some people feel compelled to taunt, tease, or otherwise belittle people with these kind of narrow and (in my opinion) useless questions.

It seems pretty plausible that they’re eaten up by the fact that they’re not as “smart” as the top guy. I think some people are using these questions to bolster their egos.

At the very least, I’d like for somebody to describe a REAL WORLD solution to a REAL WORLD problem that bore any resemblance at all to the 8 gallon jug with the 2 gallon mark problem.

You know what? You know how I’d solve this fucking problem?

I’d take my fucking fingers, and I would measure the distance from the bottom of the cylinder to the 2 gallon mark, and I’d copy the fucking line two more times. After that I’d estimate. Problem solved.

You don’t need to be fucking Archimedes to estimate how much water is in the fucking cylinder, ok?

To me, this says more about the company conducting the interview than it says about the interviewee. And the message is not encouraging:

“We hope you are good at solving problems with inadequate resources.”