Okay, let’s end the suspense! As many of you may recall, I posted an “Interview Stumper Question” article last week, featuring a logic puzzle question involving how one could identify a bottle of poisoned wine, under a time crunch, using only four mice to test the bottles.

This question was submitted to me by Michele Powell (thanks Michele!) who was asked this question recently when interviewing for a marketing position, and if needed, you can review the earlier article again by clicking here. If you do so, I highly recommend that you scroll all the way down to the bottom of the piece, where you’ll find six comments from readers who were intrigued by the scenario — and offered some great thoughts/guesses as to the answer.

My favorite answer of all to the riddle, so far? It wasn’t one of the ones posted, but actually came from a friend of mine who said. “To me, it’s simple. If you can answer this kind of question, you probably shouldn’t be in marketing.” I thought that was pretty darn funny, and will assume he meant this remark as a compliment to the creativity of marketing people, not as a slight to their intellectual gifts. Then again, he’s a software engineer, so maybe he did mean it as a “dig” at such folks, given the historical rivalries that exist between engineering and marketing folks, as chronicled by the comic strip Dilbert… :)

A similar humorous answer that a client sent me, off-line, was: “Does the answer include hitting the interviewer over the head with one bottle, shoving another where the sun doesn’t shine, and then pouring all the remining bottles down his/her throat?” He then added “This is just stupid as it doesn’t tell you anything about a person’s ability to do a job, but it does let the candidate know it isn’t the sort of place a sane person would want to work.”

And my own smart-aleck response, had I been posed with this question in an interview, might have been: “Gosh, 1-in-16 odds aren’t all that bad, and for the opportunity to work at your company, I’d drink whatever bottle you tell me to and take my chances!”

Needless to say, the above answers probably wouldn’t have gotten one very far in the hiring process! As for Michele, who was actually faced with the question, she said her first response (not expecting this kind of puzzle) was: “At first glance, taking the problem literally, you don’t seem to have sufficient time (24 hours – 24 hours) to set up the test to determine which bottle is poisoned. However, you do have 24 hours to purchase 16 new bottles of wine and save the mice, so there. Problem solved.”

While this answer demonstrated exemplary lateral thinking skills, Michele said she could tell it wasn’t what they wanted to hear, so she later sent in a more “logical” solution to the problem, which was: “Okay, assuming you have a little bit of built-in time for testing the mice, you’d arrange the bottles in a 4×4 matrix, label the four rows A/B/C/D, label the four columns A/B/C/D, and then take the four mice and label them each with an A/B/C/D tag. You’d then feed each mouse a sample of wine from its corresponding row and column and wait 24 hours. The dead mouse will correspond to a precise coordinate in the matrix. That will reveal the poisoned bottle of wine.”

As it turns out, Michele said she found out later that the above answer was not quite correct, since it would end up leaving two possibilities if a pair of mice dies, versus a single mouse. So what’s the right answer? Well, it gets pretty complex, so rather than to try and type it all out here, I’ll simply steer you to this link instead. As it turns out, this question was apparently asked as a recent “puzzler” on NPR’s Car Talk radio show, and the listeners of that show provided AMPLE discussion on how to solve the problem at the link above — including the 16-bottle version, which you’ll find if you scroll down to answer sent in by the guy named PloppityDrown.

Needless to say, these kinds of questions always make my brain hurt, and similar to some other readers, I tend to get paralyzed by the number of “assumptions” in these problems that aren’t stated clearly at the outset. Still, I suppose if a company really wanted to hire somebody who thought along these kinds of logical/mathematical lines, this would be one way to assess such things. Thanks to all of you out there who weighed in with an answer, insight, or guess!

Paul BarrowApril 4, 2010 at 3:25 amHi Matt

I am new to your blog, however, this interested me.

Well, the 4 mice 16 bottles and 24 hours is actually a classic case to test the way the mind works. This is not an untypical business scenario where you have a finite number of workers, and more problems than can be addressed (16 bottles) within the time frame (24 hours).

Most managers will opt for the simple solution of either a) hiring more mice, or b) making the mice work over time (i.e. dose them with 4 bottles each at once – if one dies you have a fair bet that it drank the poison). At worst, you have a fatality brought on by over work (stress) at best you have a happy work force earning lots of $ in overtime.

What has to be considered against either of the above is two other possibilities namely c) is it mandatory that the bottles be drunk at all, and d) is it feasible to negotiate a more reasonable deadline for the task to be carried out. A manager that thinks in terms of these is more likely to succeed in a competitive environment rather than one that panics and opts for conventional wisdom.

Hope you find this solution thought provoking!

Happy Easter

Paul

Paul BarrowApril 4, 2010 at 3:25 amHi Matt

I am new to your blog, however, this interested me.

Well, the 4 mice 16 bottles and 24 hours is actually a classic case to test the way the mind works. This is not an untypical business scenario where you have a finite number of workers, and more problems than can be addressed (16 bottles) within the time frame (24 hours).

Most managers will opt for the simple solution of either a) hiring more mice, or b) making the mice work over time (i.e. dose them with 4 bottles each at once – if one dies you have a fair bet that it drank the poison). At worst, you have a fatality brought on by over work (stress) at best you have a happy work force earning lots of $ in overtime.

What has to be considered against either of the above is two other possibilities namely c) is it mandatory that the bottles be drunk at all, and d) is it feasible to negotiate a more reasonable deadline for the task to be carried out. A manager that thinks in terms of these is more likely to succeed in a competitive environment rather than one that panics and opts for conventional wisdom.

Hope you find this solution thought provoking!

Happy Easter

Paul