I am looking for a good logic question that I can use in an interview. I was asked one years ago that I thought was effective; unfortunately, I can’t remember what the question was. Ideally, it will take some time to figure out and will provide insight into the candidate’s reasoning ability and thought process.
I spent the last 2 hours searching google & others … most of what I came across were sample questions commonly asked at interviews: “name your greatest accomplishment”. Not what I was looking for. The interview is for a quality assurance position, if you’re wondering.
Tell the interviewee to use quality assurance criteria to analyze something about her/himself. That way you can get a feel for their job-related skills and get to know a bit about them, whether relevant to the job or not (room cleanliness, eating habits, coloring book skills…).
A typical question I ask QA people is:
A product has a standard “open file” dialog box. Give me some test cases. (I’m in the software world; your world could be completely different. In software, the “open file” dialog is pretty universally understood).
What I’m looking for in this question is lots of test cases, covering real stuff. for example:
Try opening a file with a very long name
Try opening a file that doesn’t exist
Try opening a file that is many directories deep
Try opening a file that is already open by another application
Try opening a file, closing it, and opening it again
Test case sensativity in a file name
etc.
I think what you’re really looking for though are questions like this:
You have a cube 3" on each side. You can cut it into thirds in each dimensions, so that you have 27 1" cubes. This requires 6 cuts (2 per side). Say after the first cut you stack the two cut pieces on top of each other and cut through both of them. By repeatedly doing this, can you cut it into the 27 cubes with fewer than 6 cuts?
You have a checkerboard with 64 1"x1" squares. You also have 32 dominoes, each 1"x2". You can cover the checkerboard with the dominoes. Now we remove two squares from the checkerboard, the upper left square and the lower right square, leaving us with 62 squares. Can you cover the checkerboard with 31 dominoes?
A man walks up a hill starting at 8am and arrives at the top at 6pm. He sleeps, wakes up the next morning, and walks down the hill starting at 8am and arriving at the bottom at 4pm. Is he ever in the same place at the same time on both days?
Both very good. I plan to use the “File Open” question. I asked a similar question previously, but it was quite a bit longer (picture of a form screen from our application … which test cases would you execute?). Your question will provide the same insight in much less time.
As for the puzzles … yes, that is more of what I was searching for. Those are pretty damn hard, though, and I might scare off a few if I chose to use them. But maybe that’s not such a bad idea :eek:
Whatmove: It’s pretty difficult to get warm fuzzies on the SD, so I appreciate the welcome note.
There are four guys who need to cross a bridge, and one flashlight. Only two can cross at once. The first guy takes 1 minute to cross, the second takes 2 minutes, the third takes 7 minutes, and the fourth takes 10 minutes. How can you get them all across in 17 minutes?
There was a similar brain-teaser, but I can’t remember it. You might want to just get a book of brain-teasers or lateral thinking puzzles, and see what you can find in there.
You have a room with three lights. The switches are outside the room and you can’t see the lights when you are by the switches. How do you determine which switch controls which light, when you can only enter the room once. (Answer: Turn two lights on, wait a minute, turn one switch off. When you go into the room, you will have one lit bulb, one unlit bulb that is cold and one unlit bulb that is warm)
You have a 5 oz. glass and a 3 oz glass. How do you measure one oz. of water? (A little harder - fill the 5 oz glass. Fill the 3 oz. glass from the 5 oz glass. Throw out the water in the 3 oz glass, then pour the remaining 2 oz in the smaller glass. Fill the 5 oz glass again, then top of the smaller glass. Now you have 4 oz of water - throw out the water in the smaller glass and fill it up with the water from the larger glass. Now you have 1 oz of water in the larger glass)
Both of these are from when I interviewed with Microsoft. I got the first one in the interview. It took me 24 hrs to get the second one.
When I interview for QA positions, I generally get
[ul]
[li]Test this generic feature (save, file open, print, search)[/li]
[li]Test this simple computer program (it takes in two numbers and plots a point, it takes in three numbers and tells you something about a triangle, it takes in a list of words and alphabetizes them)[/li]
[li]Test a familiar object (Soda machine and stapler seem to be favorites. Once someone wanted an alarm clock).[/li]
[li]Logic problems[/li][/ul]
I actually like the logic problems. But I’m odd that way. One thing about them, I would guess most candidates have heard most of the major logic problem themes (I can only remember being really thrown three times. One I was told the answer, one took me 15 minutes where the interviewers just stared at me and giggled, and in the third, anyone who had grown up where the nearest and most familiar islands were practically rainforest was going to miss the answer.) So I’m not sure they’re giving the information that the interviewer thinks they give.
There’s always the classic: Which six/seven/eight famous people would you invite to a dinner party and why ?
Depending on how/whether they pick up on juxtaposing social mix, genders, etc with integrating the personalities of the people they choose, you get a good insight into how they think and how quickly. As well as the kinds of people they are interested in.
As an interesting sociological comment, I’d like to point out that I’m from a very different profession than most of you all (the law) but one that nonetheless relied on logiv to a heavy extent. Were I to have been asked any brain teasers at my interviews, I’d have gotten up and walked off right then, convinced that the interviewer simply wasn’t serious about filling the position and was merely on a power trip.
I’m with Cliffy – versions of the question I suggested have been used in legal interviews. You have the basic qualifications already so the interview is not about ability. Instead, it’s about demonstrating how you think, how quickly and personality/character. Maybe it’s different in other fields where qualifications aren’t a given.
You could give them the classic thinking-outside-of-the-box problem. You know, the one where you have 3 rows of 3 dots, all equally spaced apart (9 dots total). You ask them to connect all of the dots in just 4 lines, without lifting the pencil/pen. (The solution requires the lines to go outside of the box.)
An IT interview question that’s relevant to QA. Something like:
“It’s Wednesday morning, the shipment/product/release has been promised to the customer by COB Friday and you’ve discovered that there are quality problem/bugs. You estimate that with the resources available fixing the problems will take 55-60 hours or so… what do you do? Fix what you can and release with outstanding problems? Not release? Work 3 x 20 days to get the problems all fixed… or something else?”
We found this one got some people squirming as they were trying to guess whether they should say “20 hour days”… (which people with more experience will generally know is not a good solution).
The best answer I heard to this went along the lines of:
“First I contact the customer and reset expectations. I’ll explain that I won’t release with bugs and move the delivery date to Monday, that gives me 2 extra days. 5 x 11-12 hour days can be done, though it’s probably better to work out which of the problems can be deferred, even if we have to tell the customer of some known problem areas”.
Just a note, you’ve made that 5oz/3oz puzzle wayyyy too hard. Here’s an easy solution…
Fill 3oz, pour that into 5oz.
Fill 3oz, fill rest of 5oz with it.
You have 1oz left in the 3oz cup.
The problem with these, is that some of these problems will sometimes show you problem solving skills, and sometimes not. The question about the 64 tiles and the dominoes is one that requires some time to figure out. It’s not too difficult, just something that requires visualization, and it’s such a large board that not many people can visualize it in their head, so they’ll need paper. What, exactly, does that puzzle show you about someone?
Why not pick something that’s a real world problem. If it’s an IS job, ask how they would design a small LAN, needing two separate networks that went through one external internet connection.
Apollyon also has a very good suggestion to a question, but it’s more of a managerial (sp?) question rather than a technical one. Still, I think it works quite well for an interview, as it has a very real possibility in the real world. I can’t think of many times my boss has run to me, asking if he can fit 31 dominoes into a board of 62 squares.
Several more good ones; I’m glad I posted this! Two more days to gather up some toughies before the interviewees start rolling in.
I did want to throw one more clue in here … a partial memory of the original puzzle that I really liked. It went something like this:
Joe, Fred, person X,Y,Z all lived along some River
Joe lived at the top
Fred was afraid of squirrels
PersonX …
and so on until you have to figure out what order their houses would be in from North to South. Many questions like this are fairly easy to figure out (GRE test questions). The one I was given, however, was pretty difficult. I figured it out in the allotted 15 minutes and pretty much shocked them (little did they know it was really just a lucky guess ). What interested me, however, was that it was intended to be tougher than a 15 min answer … they required you to write down your thought process and used this to analyze your reasoning abilities.
No real visualization required. Opposite corners of a chess board are the same color. Each domino must cover one white and one black square. Regardless of how you place the first thirty, you will be left with two squares of the same color, and only one domino. Thus, it is impossible.
I’ve seen this problem used to demonstrate the difference between mathematicians and engineers (or even physicists). The mathematician solves it like I just did; the physicist/engineer sits down with a chess board and 31 dominoes and tries every which way from Sunday until he’s convinced himself that it’s probably not possible.
Of course, the three light bulb problem does just the opposite. The mathematician starts writing out formulas to figure the minimum number of trips, whereas the more practical minded man comes up with the solution of touching one of the bulbs.
). What interested me, however, was that it was intended to be tougher than a 15 min answer … they required you to write down your thought process and used this to analyze your reasoning abilities.