Pokmon McDonald's is giving away a pack of 5 different Pokmon cards with every Happy Meal. There are in total 25 unique Pokmon cards which are being given away. Assume that any 5 of these cards are equally likely to show up in a given Happy Meal. Hint: Read this problem carefully. (a) Given that Pikachu is one of those 25-Pokmon, find the chance that Pikachu appears in a Happy Meal.