#48 The solution provided doesn't seem to answer the right question. The question in the problem is "In order to ensure that the sum of all cards he drew was even, how many cards did Jerome have to draw?"beatthegmat wrote:Found this great set of probability and combination problems. Remember--these types of questions appear infrequently on the GMAT, so don't over-emphasize them too much in your studies!

The solution says: The 12th draw ensures an even sum.

Let's assume Jerome drew 12 cards and there are 9 odd cards and 2 even cards, so the sum is ODD

If he drew 13 cards, 9 odds and 4 evens, the sum is still ODD.

SO he has to draw all 20 cards to ensure that the sum is EVEN.

I assume that he is not calculating the sum upon drawing every next card, because the condition doesn't say so..

Is my logic wrong here?