Fiona is not correct because a larger part of the square is white.
Fiona guesses that the coin is likely to land in the blue area. Here, Fiona is not correct because a larger part of the square is white.
As we can see the attached picture, there is a major white part. The blue part is not even half. It is less than half. The probability decreases here as the blue part is less as compared to white part. If blue part would have been more then Fiona's guess would have been right.