GMAT数学错题.doc

If x and y are positive, is?(1)(2)x ＞ y AStatement (1) ALONE is sufficient, but statement (2) alone is not sufficient. BStatement (2) ALONE is sufficient, but statement (1) alone is not sufficient. CBOTH statement TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. DEACH statement ALONE is sufficient. EStatements (1) and (2) TOGETHER are NOT sufficient. 可以举出符合上述2个条件的例子证明体重不等式既可以大于也可以小于，所以C是错的 当x, y都为0~1之间的数，则都不成立手痒，写写思路条件一 ? 无法确定 x是否大于1，所以不充分因为只有?x^3 ?x^(1/2)y 时才能得出?结论（此时，x1）条件二 无法确定x是否大于1，所以不充分?只有x^3xy 时才能得出 x^3y 可以举出符合上述2个条件的例子证明体重不等式既可以大于也可以小于，所以C是错的 1.x=o.o4,y=0.01 符合条件（1)和（2），这时题中不等式应为x^3y 2.x=4,y=1 符合条件（1)和（2），这时题中不等式应为x^3y 因此即使2个条件都用也无法判断x是否大于1,从而不能判断 By what percent was the price of a certain television set discounted for a sale?(1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price.(2) The price of the television set was discounted by $60 for the sale. AStatement (1) ALONE is sufficient, but statement (2) alone is not sufficient. BStatement (2) ALONE is sufficient, but statement (1) alone is not sufficient. CBOTH statement TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. DEACH statement ALONE is sufficient. EStatements (1) and (2) TOGETHER are NOT sufficient. 设电视机打折后价格为x，打折前则为125%x,那么折扣可以表示为(125%x-x)/125%,条件一是充足的，条件二单独没有用。 During a trip, Francine traveled x percent of the total distance at an average speed of 40 miles per hour and the rest of the distance at an average speed of 60 miles per hour. In terms of x, what was Francine’s average speed for the entire trip? A（180-x)/2 B(x+60)/4 C(300-x)/5 D600/(115-x) E12000/(x+2) X% traveeled at 40 mph100-X% traveeled at 60 mphtotal timt taken = x/40 +(100-x)/60 = (200+x)/120Total distance = x+(100-x) = 100Av speed = Tot Dis/Time Taken which is E 错在题目问的是速度，而我计算出时间C就直接作答，审题不细 What is the value of??(1)x = 2(2)y = 3 AStatement (1) ALONE is sufficient, but statement (2) alone is not sufficient. BSt