Accuracy of the Gruber's complete SAT guide?

<p>Hey CC,</p>

<p>I just bought the Gruber's complete SAT guide for the december sat. I took the 3 math sections on the first practice test and scored a 680 =(. What is the accuracy of these practice tests? Also, im looking to improve my CR(620) 60-70 pts, my writing(600) 60-70 pts and my math 100 pts. I took the 101 questions you should know the answers to and only got 1 wrong so im not sure going through the math refreshers would do me much good. What sections of the book should I use in the coming month to meet my goals on the SAT? Thanks!</p>