# Mensa Romania IQ test question - triangles and circles

Can somebody tell me what is the answer to this puzzle? And why?

Thanks!

• Welcome to Puzzling! This is not a [logic-puzzle]; please check the tag wiki before using a tag.
– Deusovi
Commented Jul 27, 2016 at 13:29
• The literal answer to your question would be "Yes. Because people here are smart." since you asked "Can somebody tell me?". But probably not the answer you were looking for. Commented Jul 27, 2016 at 13:37
• Hope you're not asking from the examination hall :P Commented Jul 27, 2016 at 17:27
• Are you sure it's OK to repost the question here?
– WBT
Commented Jul 28, 2016 at 0:39
• For some reason that domain is blocked at the place I'm working. Can you please upload that picture via upload feature(to i.stack.imgur)? Commented Jul 28, 2016 at 16:08

It is

C

Because the third column

is the difference between the first and second column

• Also works if you look at rows instead of columns. Commented Jul 27, 2016 at 13:37
• Ha - that's surprising but true. Commented Jul 27, 2016 at 13:38
• Easier to see and two direction variant of the puzzle puzzling.stackexchange.com/questions/38009/…
– z100
Commented Jul 27, 2016 at 15:24

C

Because of

• Hello, and welcome to Puzzling.SE! It is customary to hide your answer with spoiler tags >!. Also, adding a duplicate answer is typically frowned upon unless you can demonstrate a substantially different method of getting there than has been previously mentioned. Commented Jul 27, 2016 at 18:03
• +1 because, except the edit, the answer is good.. but a bit developer way... you may explain XOR Commented Jul 27, 2016 at 18:07
• Added documentation link for XOR operator. Commented Jul 27, 2016 at 20:33
• The XOR principle was covered in earlier answers and comments. Commented Jul 27, 2016 at 22:51
• This is the cleanest and most specific answer, and an improvement to the previous.
– pipe
Commented Jul 28, 2016 at 8:51

C

Explanation:

Each column and row has exactly 2 circles.
Each of the four corners appears an even number of times in each column or row.

• It looks more to me like you take both pictures, stack them on top of each other, and remove any overlap Commented Jul 27, 2016 at 13:33
• @Areeb Different wording but same effect. Commented Jul 27, 2016 at 13:35
• Or you could say "XOR the shapes", I believe this sums it up perfectly. Commented Jul 27, 2016 at 17:39

It is

C

Because :

It works by column, and the third picture depends on the two first.
On the last symbol of the line, you add the symbols of the first and second pictures. If a form (triangle or circle) is present twice, you remove it. Else, you leave it. For example, for the first column : You add the first picture :
(1 triangle at the top right corner and 1 at the top left corner, and 1 circle at the middle), and the second one :
(1 triangle at the top right corner, 1 at the bottom left corner, 1 at the bottom right corner, 0 circle in the middle), so you get : 1 triangle at the top left corner, 2 at the top right, 1 at each bottom and 1 circle, so you just remove the top right one and it gives you the picture at the third line of column number 1.

C

Because:

The third picture in each row is the first picture plus the second picture, but with a bit of a twist. If a part of the first picture overlaps with another of the second picture, then remove that part when adding the pictures. Or else, continue with the addition. I've also made a picture so that it is clearer:

The parts in red are the parts to be removed, and the others in black are the parts to be combined to form the third picture. Hence, the answer is C, as C is the picture formed when the black parts of the first two pictures of the third row are combined.

I think it is simpler - It is

E

I see two rules:

1. If you scan the rows from the top in rows (vertically) or horizontally in columns, there is a rule that there are always two black solid circles in every row. So we are missing something with a solid black circle, possible answers are A, C, E.
2. All of the solid black circle symbols can be paired off as mirror images of each other, like this:
(a) the bottom left symbol is a mirror image of the middle one in the far right column.
(b) The one in the middle of the top row, is a mirror image of the one in the centre of the middle row.

Following this rule, the un-paired solid black remaining is the one at the top left. A mirror image of this is symbol E.

I'm assuming the three white square symbols (with no solid black circle), are just distractions/noise.

• Never assume that there is "noise" in these puzzles. Commented Jul 27, 2016 at 17:08