According to the problem, we have four cards, where one of them is 6. So, the probability of picking 6 is the quotient between the number of cards with six and the total number of them.
Because there's just one card of six and there are 4 cards in total.
Now, we multiply the decimal number by 100 to express it as a percentage.
P = 0.25*100 = 25%.
Therefore, the probability