What is the answer to this IQ test problem? Justify your reasoning.

IQ test problem

  • 4
    $\begingroup$ Can you provide attribution (i.e. where you got this puzzle from)? $\endgroup$ – Glorfindel Dec 28 '16 at 9:30

My answer is

Fourth picture

Pattern (on the left side):

Assume the dotted line is a path, and you need to follow it (we are look at the left of the puzzle right now). Then black dots do not affect your path. However when we reach a white dot we go around it, turning twice. Then we check to see if we are next to any other white dots, and if we are we go around that twice again. If not then we keep going straight. Furthermore, if we crash into a side of the box we turn, and the path never self-intersects. Last thing we notice is that the path must visit all the places which are corners of the dots

Reasoning for the right side:

We can get this:
enter image description here
Now if the top right dot is white then the paths must intersect before reaching the bottom. Thus it is black.
enter image description here
We can get this next. Note that the top left has to be black. If the bottom left is white then again they join too early, thus it is black. Lastly the bottom right must be white because if it isn't then the paths don't join.

  • 1
    $\begingroup$ Find this puzzle worth writing up and illustrating a solution? Why not give it a vote of approval? $\endgroup$ – humn Dec 28 '16 at 12:36
  • 1
    $\begingroup$ At work, I deal with lots of cases where I need to provide good answers to questions. That doesn't mean those questions are, necessarily, good. "I can provide an answer to this question" and "I think this question is a good one" are different things entirely, and I think it's entirely possible for someone to provide an answer to a question they have already downvoted, or end up downvoting, without this being any kind of contradictory behavior. $\endgroup$ – Rubio Dec 29 '16 at 8:26
  • $\begingroup$ Dear @Rubio, my question was addressed to the answer's poster. A more general question is: Why not leave the solving of a puzzle to someone who appreciates that puzzle? The solution would likely be better presented, in most cases, so the rewards all around will be more meaningful than parasitic vote points. Puzzles here are not nearly as urgent as questions at work. $\endgroup$ – humn Dec 30 '16 at 22:42
  • $\begingroup$ @humn Currently it is holidays for me and I am really bored at home. I am constantly looking for new puzzles to do so when I saw this one I thought about it. Since I already had a solution I might as well write it up right? $\endgroup$ – Wen1now Dec 30 '16 at 23:49
  • $\begingroup$ No need to write it up, @Wen1now, someone else would have come along to take care of that, hopefully with more interest in the puzzle. For example, there is a more interesting, simpler, pattern that could be mentioned but isn't represented in any of the choices. (White circles have 3 bypasses, black circles have 2, which is a surprisingly difficult pattern to accomplish on an arbitrary layout of circles and could be the basis of a good other puzzle.) $\endgroup$ – humn Dec 31 '16 at 0:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.