GMAT Prep Sufficiency Questions (2)

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GMAT Prep Questions



Data Sufficiency  



以下问题大部分是我做GMAT Prep 做错过的题目，所以没有正确答案，只有错误答案。不找出错的原因我心里很不舒服，希望CDer能多多帮忙，谢谢！



1.         If ab ≠0 and points (-a,b) and (-b,a) are in the same quadrant of the xy-plane, is point (-x,y) in the same quadrant?

(1)    xy>0

(2)    ax>0



答案不是A, 是C吗？





2．  Store S sold a total of 90 copies of a certain book during the seven days of last week, and it sold different numbers of copies on any two of the days. If for the seven days Store S sold the greatest number of copies on Saturday and the second greatest number of copies on Friday, did store S sell more than 11 copies on Friday?



(1)   Last week Store S sold 8 copies of the book on Thursday.

(2)   Last week Store S sold 38 copies of the book on Saturday.



答案不是E，答案是B么？



3．  If 500 is the multiple of 100 that is closest to xand 400 is the multiple of 100 that is closet to y, which multiple of100 is closet to x+y？

（1）     x<500

（2）     y<400

答案不是C答案是什么啊？





4．  Is the integer n odd?

(1)    n is divisible by 3.

(2)    2n is divisible by twice as many positive integers as n.



答案不是C





5．The operation o represents either addition, substration, or multiplication of integers, what is the value of 1 o 0?



(1)    0 o 2 =2

(2)    2 o 0=2



答案不是A，答案是D么？





6．Is x^4+y^4>z^4?

(1)    x^2+y^2>z^2

(2)    x+y>z

答案是E，为什么?