# Old Mensa Norway Question 32 - lines above a square

The answer is the option in the spoiler, but I can't quite figure out why.

D (bottom left)

Source: This question was on the Mensa Norway IQ Test, but now is on the Mensa Finland IQ Test.

• Has a useful answer been given? If so, please don't forget to $\color{green}{\checkmark \small\text{Accept}}$ it :)
– Rubio
Aug 8 '19 at 3:19

I'm not a fan of these types of puzzles but I think the reasoning is as follows

Rotate the central diamond image $$45^o$$ anti-clockwise so that their edges are now horizontal and vertical.
Then, in each row, if we take the XOR value of the edges surrounding the left square with the edges surrounding the middle square, we obtain the edges surrounding the right square.

In particular, on the bottom row, the left square has got an edge on its right-hand side and the middle square will have edges on its top and left. The result of taking the XOR of these edge values is a square with edges on its top, left and right. This is the image in the bottom left of the possible answers.

• I'm just typing the answer :P Aug 6 '19 at 9:22