jj-18

qiufeng1990

9、7 positive integers, 5 are odd, 2 are even. First pick up 4 out of them and get the sum of them, then pick up 2 from the rest and also get the sum. Which of the following must be true?
(1)at least one of the sums is odd; (4odd,　２even)
(2)at least one of the sums is even; (3odd1even, 1odd1even)
(3) the sum of the two sums is even. (4odd, 1odd1even)
【机委】NONE。
我选了I，可能是把机经记错啦。
------------------------------------
II。感谢cook的指点！！
滚据解释，是【机委】NONE。????? why II?

tongxun

确实有过这么一题，谢谢pgclt！

pgclt

I remember the original problem is products, not sums. that may explain why 2).

tongxun

对！我与cook把两个和都加起来了。烦请以后有机警讨论多提点！