Combination problem with repetition. GRE Anagram Grid questions. Why do we divide?
If 3 of 7 standby passengers are selected for a flight, how many different combinations of standby passengers can be selected? So the answer to do this I think is 7! / (4! * 3!) The standby passengers **and** the flying passengers are both indistinguishable or rather order doesn't matter. But again, why aren't we subtracting? Why are we dividing?