Trying this again: To stay within one color, the coin's center must remain within a square with 0.5" sides, which would have an area of 0.25. So probability of touching another color = 0.75.
The alternate scenario (which I don't think was the intent) is that the coin touches another color, but only in one other square. In the photo, only the lower right coin satisfies this condition. There are four areas where this could happen, 0.25 x 0.50 each, so that probability would be 0.50.