# A quick puzzle from the Mensa Romania test

Can somebody tell me what's the answer on this puzzle? And why?

Thanks!!

• Welcome to Puzzling! This is not a [logic-puzzle]; please check the tag wiki before using a tag. – Deusovi Jul 27 '16 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. – Floris Jul 27 '16 at 13:37
• Hope you're not asking from the examination hall :P – ABcDexter Jul 27 '16 at 17:27
• @ABcDexter Yeah, that would be a slight edge... – Revetahw Jul 27 '16 at 19:02
• Are you sure it's OK to repost the question here? – WBT Jul 28 '16 at 0:39

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. – The Dark Truth Jul 27 '16 at 13:37
• Ha - that's surprising but true. – Floris Jul 27 '16 at 13:38
• Easier to see and two direction variant of the puzzle puzzling.stackexchange.com/questions/38009/… – z100 Jul 27 '16 at 15:24

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 – Areeb Jul 27 '16 at 13:33
• @Areeb Different wording but same effect. – The Dark Truth Jul 27 '16 at 13:35
• Or you could say "XOR the shapes", I believe this sums it up perfectly. – Anton Jul 27 '16 at 17:39

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. – feelinferrety Jul 27 '16 at 18:03
• +1 because, except the edit, the answer is good.. but a bit developer way... you may explain XOR – lemon Jul 27 '16 at 18:07
• Added documentation link for XOR operator. – Ashish Jain Jul 27 '16 at 20:33
• The XOR principle was covered in earlier answers and comments. – Prune Jul 27 '16 at 22:51
• This is the cleanest and most specific answer, and an improvement to the previous. – pipe Jul 28 '16 at 8:51

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.

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. – Floris Jul 27 '16 at 17:08