Hi, I am studying for the GMAT and there is an example in one of my test prep books that does not make sense to me.
"a man has 5 shirts. If he has to bring 2 shirts, how many possible arrangements are there? Order does not matter"
The formula it says is C(5,3) 5!/(5-3)!*3!
What I can't understand is why m=3 instead of 2. If it's arrangements of 2 shirts, why isn't it C(5,2) 5!/(5-2)!*2!
Although correct, the GMAT answer is going to confuse many students. Answers often suggest the approach - in this case it is obvious where C(5, 2) comes from, it is much less obvious (and this thread is a case in point) where C(5, 3) comes from. 'Unselecting' is not the natural approach for this question and beginners will find the GMAT answer confusing. In my opinion, it is a correct but not a good answer.