# TEST QI puzzle - squares and circles on a 4x4 grid

This puzzle comes from an IQ test app called TEST QI. I cannot understand why the yellow option (the first option on the bottom row) is the right choice. Any idea?

Think this is it:

A sequence of infinitely long square/not square is moving across the board from top to bottom, left to right in backwards diagonals so you have the squares right.
A sequence of circle-no circle-circle (just those 3) is moving horizontally top to bottom left to right 1 space at a time. Often they are behind the squares. Its right side starts in box 3. As they move alternate between open and closed every other move. The open circle alternates on it's first move, the closed circle on it's 2nd move, then they alternate every other move after the initial alter. (i.e. an odd even pattern)

• I am not sure to have understood the pattern of the dots and circles. Jul 29, 2020 at 15:58
• For those looks like the dots as they move alternate between open and closed every other move. The circle alternates on it's first move, the dot on it's 2nd move, then they alternate every other move after the initial alter. (i.e. an odd even pattern)
– Amoz
Jul 29, 2020 at 16:03
• I agree mostly with your answer but I think the interpretation is that the circles change from hollow to full or vice versa when they are covered by the squares. It would be useful to include a diagram in your answer just to illustrate. Jul 29, 2020 at 16:32
• That is more intuitive. The squares are like little factories that manipulate the circles. It seemed like there was a relation but I wasn't quite seeing it.
– Amoz
Jul 29, 2020 at 16:42
• Following the tip of hexomino I finally understood. Nice catch! Thank you all. Jul 29, 2020 at 17:02

## To solve this problem, we first need to understand 4 patterns present in the image

1. In each square of the matrix, from left to right, 1 white square is added, observe the image:

2. From top to bottom, the white ball moves one space at a time in a southwest direction, observe the image:

3. From left to right, the white ball that I will call "almost white" first moves one space forward and then moves down one space in the southwest direction, observe the image:

4. After this analysis, all we can do now is differentiate the letter D from the letter E or the first option on the bottom line/last option on the top line.

As you may have already noticed in the answer box, due to the movement pattern of the balls they will appear in the same place, now we have to know which ball will remain on top of the other,

If you've been paying attention, you'll see that this has already happened in the first column of the matrix, look at the image:

As we can see, the almost white ball stands out over the white ball and we finally solve the problem leaving only the letter 'E' or the first option at the bottom. :v