The answer is 3/13.
To win, Katie need to get one of the cards she bets on. There are in total 26 cards and of those cards 6 of them are face cards (J, Q, and K spades and J, Q, and K clubs). Therefore, the probability to get on of these 6 cards and, thus, the probability that Katie will win this round is 3/13:
P = 6/26 = (6÷2)/(26÷2) = 3/13
