Manhattan GMAT CAT

[spd8906]

Hey everyone.. I am new on the forum.. A little bit about myself, I am a student at a CUNY college and I am about to graduate in January of 2011.. I have a double major in Finance and International Business. I am looking into going to grad school and I started studying about two weeks ago for my GMAT. I know its not enough studying but I am expecting to take the actual thing on December 6th. I went through the whole set of Manhattan GMAT books on my own except for the geometry book. I started taking the CATs recently and my first one was a 590, the second was a 610 and the third one was a 640. I took them all timed just like the actual exam, did the essays and everything. My latest score, the 640 was a Q:44 and V:35. How accurate are these Manhattan GMAT CATs, in terms of the questions and difficulty and all?? I've been going through all the problems in the GMAT official guide as well and those seem significantly easier. They also claim that the official guide's questions are from actual past GMATs. So again, how accurate are these MGMAT CAT scores?? Also, any suggestions on how to approach the data sufficiency questions would be nice. I tend to suck at those. I've a 3.9 GPA so I am really hoping to at least get a 620 - 650 GMAT and a 700 would be nice. I know I didn't prepare enough but its a lack of time thing.