wait is the chance of winning ups, unupps, or just winning
Technically, he increased the number of ungraded cards in a halfblood's deck from 15% to 30%, making it about twice as likely to win an upgraded card. So now it's about 2%.
i think that the actual chances of winning at least a card (that means 1, 2 or 3) is 2,6% [I used binomial distribution with n=3, r=0,1,2,3 and p=0,008 (1/5^3)]
Now the chances of that card being unupped or upped is: 2,6*0,7 for unuped and 2,6*0,3 for upped.
(I assumed all 5 cards selected by the slot machine are different, it gets roughy and calculating if 2 are equal)