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题库 / Prep2007E2-DS-155
If 500 is the multiple of 100 that is closest to x and 400 is the multiple of 100 that is closest to y, which multiple of 100 is closest to x + y ?
(1) x < 500
(2) y < 400
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
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本题错就错在没看到标色部分，
“500 is the multiple of 100 that is closest to x”转换为不等式就是“450≤x＜550”
“400 is the multiple of 100 that is closest to y”转换为不等式就是“350≤y＜450”
∴ 如果（1）成立，则450≤x＜500，800≤x+y＜950，无法确定其multiple of 100是800还是900
如果（2）成立，则350≤y＜400, 800≤x+y＜950，无法确定其multiple of 100是800还是900
如果（1）+（2），则800≤x+y＜900，依然不知道该数是距离800近还是900近。
想问X在450与550之间是怎么得出的呢。。
我觉得主要是closest to A在数学方面的理解是表明在以A为中心的区间。这道题我也不太理解，后来去国外论坛看了别人的解答。类似的还有一些，我明天在og找找
哦哦！这题我看论坛上都是这个解答 但就是不理解呢
“500 is the multiple of 100 that is closest to x”转换为不等式就是“450≤x＜550”
为啥是≤，不是
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