Permutations and Combinations.In some questions (like the one given below) we come across a dilemma to either to add or to multiply. Please tell me how do you do these type questions?Ex--4 cards are chosen from a pack of 52 cards.In how many of these --a)Four cards are of same suitb)two are red cards and two are black cards.In case (a) we add but in case (b) we multiply.Why?Thanks

Nitin Gupta , 14 Years ago

Grade 11