Always choose the circle
The following is the probabilities of a certain card type appearing once a decision is made.
Wavy line: 17%
Square: 18%
Circle: 22%
Triangle: 18%
Cross: 11%
Plus sign: 14%
In conclusion, always choose the circle. It gives the biggest chance of a correct guess.
Here’s another research conducted into Guess the Card percentages by TwilightWillow
Ok so I was definitely up past midnight tonight playing Guess the Card 100 times – yes you heard me correctly – 100 times so I could get some accurate percentages on the cards. This is what I found:
Circle: 14%
Cross: 16%
Square: 10%
Triangle: 20%
Plus: 27%
Wavy lines: 13%
But here are some other things I saw: A lot of times, the cards will come in twos. For example, if the card your pet guesses is a triangle, it has roughly a 5/9 chance that he will guess triangle again immediately after. Another thing is, the plus sign was the first sign my pet guessed, cross didn’t come in until 3rd guess, wavy lines fourth, square seventh, circle tenth, and triangle twenty-first. So keep this in mind depending on how many times you plan on playing.
Here is the play by play guide to my 100 games if you want to search for your own patterns:
1-plus, 2-plus, 3-cross, 4-wavy, 5-wavy, 6-plus, 7-square, 8-plus, 9-square, 10-circle, 11-wavy, 12-wavy, 13-cross, 14-plus, 15-wavy, 16-wavy, 17-cross, 18-circle, 19-plus, 20-square, 21-triangle, 22-cross, 23-triangle, 24-circle, 25-plus, 26-cross, 27-cross, 28-square, 29-cross, 30-cross, 31-circle, 32-wavy, 33-plus, 34-square, 35-circle, 36-circle, 37-triangle, 38-plus, 39-square, 40-cross, 41-triangle, 42-triangle, 43-cross, 44-plus, 45-wavy, 46-circle, 47-triangle, 48-circle, 49-cross, 50-wavy, 51-triangle, 52-triangle, 53-triangle, 54-square, 55-plus, 56-plus, 57-triangle, 58-triangle, 59-plus, 60-circle, 61-plus, 62-wavy, 63-triangle, 64-plus, 65-triangle, 66-plus, 67-triangle, 68-cross, 69-cross, 70-square, 71-cross, 72-plus, 73-triangle, 74-triangle, 75-circle, 76-circle, 77-plus, 78-plus, 79-wavy, 80-plus, 81-plus, 82-wavy, 83-plus, 84-triangle, 85-cross, 86-plus, 87-circle, 88-triangle, 89-cross, 90-square, 91-plus, 92-circle, 93-plus, 94-triangle, 95-plus, 96-triangle, 97-square, 98-plus, 99-wavy, 100-circle. – Benubird