请教GWD4的一道数学题

fangfanggmat · 发表于 2015-11-18 14:27:47

Q32:

Is the integer n even?

(1) n – 5 is an oddinteger.

(2) n/5 is an even integer.

A. Statement (1) ALONE issufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE issufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHERare sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONEis sufficient.

E. Statements (1) and (2) TOGETHERare NOT sufficient.

Answer:

答案是D.

我不理解A。如果n=-1,n-5=-6，是偶数。那么不能证明n是偶数，所以条件1不成立。

哪里错了？谢谢！

Bill06052002 · 发表于 2015-11-18 14:44:14

A是說n-5=一個奇數整數，所以不會等於-6 你的舉例有問題

wtpmjgda · 发表于 2015-11-18 14:45:44

5是奇数奇数加奇数等于偶数所以对于条件1 就是n = 5+奇数=偶数能判断n的奇偶 sufficient
对于条件二奇数x偶数=偶数能判断n的奇偶 sufficient
odd是奇数的意思 even是偶数的意思
故选D

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