The probability of this happening would be a 1 when placing a value between zero and one inclusive. One in this case would indicate a 100% probability. This is the case because in the question it is stated that it is "certain" that you will get 2 kings when selecting 50 cards, this means that no matter what it will happen every time 50 cards are drawn, thus making the probability 100%. If the question were phrased differently such as "what is the probability of getting 2 kings from 50 cards drawn?" then the probability would be 0.04 or 4% which is 2/50.