10 points lower = same score, basically. But that doesn't mean you're not getting better. It's very common to have about the same score on the second test, even after 1 month of study. (In our classes, we have people take the second test after about 5 to 7 weeks of study and, even then, a lot of people stay the same.)
One of the major issues is likely timing - if you haven't been working on timing as diligently as you've been working on content, then that can hold your score back.
First, I'd like to get some more detailed data on your strengths and weaknesses in order to advise you. Use the below to analyze your most recent MGMAT CAT(s):
http://www.manhattangmat.com/blog/index ... ice-tests/Next, do two things: talk to your teacher and also come back here and tell us the results of your analysis and what you think you should do based on that analysis. (Note: do share an analysis with us, not just the raw data. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)
Re: timing, read these two articles and start doing what they say:
http://www.manhattangmat.com/blog/index ... to-win-it/http://www.manhattangmat.com/blog/index ... nt-part-1/Finally, read the "How to Learn" section of this article:
http://www.manhattangmat.com/blog/index ... an-part-2/Follow the links and, again, start doing what they say. :)
Re: careless mistakes. start keeping a log. When you make a mistake, note down (a) what mistake you made, and (b) WHY you made the mistake. Then try to figure out what you could do differently next time in order to minimize the chances of repeating that exact same kind of mistake. For example, sometimes people will solve for the wrong thing - they ask for X and you solve for Y. One thing you could do is get into the habit of glancing at the question stem for 1 second after you've finished the problem but right before you pick the answer. You remind yourself: okay, I want X... oh, wait, and I just solved for Y. :)