问一题~

evelyn205205 · 发表于 2011-2-1 14:47:49

If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24, what is the value of r?
(1)2 is not a factor of n.
(2)3 is not a factor of n.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

ANSWER: C

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

ANSWER: C

evelyn205205 · 发表于 2011-2-2 10:05:49

期待各路大侠的帮助

evelyn205205 · 发表于 2011-2-2 10:41:36

帮忙一下咯，麻烦各路牛牛咯

zl8801 · 发表于 2011-2-3 00:34:41

C
because if you take 5, reminder is 0, if you take 9 reminder is 8

Same trial for 2) so, can’t be held

now 1)+2)

Imagine, if 2 is not a factor ,3 is not a factor, so N Can be 5, 7,11, always the prime number. Now (n-1)(n+1) is sure to be an even number as each is even, n-1 can be surely divided by 4, so doest n+1 and n-1 or n+1 can be divided by 3. so you can get a number like 2*4*3 so that it can be divided by 24 reminder is 0

evelyn205205 · 发表于 2011-2-3 11:27:37

问一题~

所属分类: GMAT考试

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