You were probably doing better on quant and then your score went down at the end because of the timing issues. I'm guessing that you also rushed on some in addition to outright guessing on 3, so that gave you the chance to get a lot of questions wrong in a row - which is very bad for your score.
I'm also guessing that you had timing problems on your practice tests, even if you weren't aware of it.
I also just want to mention one thing. It's extremely unlikely that you got 5 questions in the combinatorics / probability category. You likely thought you were getting more because you don't like those (right?). For the questions that count, we actually all see the same mix of topics (though different individual questions). The experimental questions introduce some leeway (they do vary by topic), but the standard count for this category is 1. You might have gotten an extra 1 or 2 as experimentals - but you didn't have 5 that counted, at the very least, and you probably didn't have 5 at all. :)
Right now, you're probably thinking, "No way! I remember it!" I had another student tell me something similar one time about one of his practice tests. I knew this was impossible because we limit the # of questions in those categories, so we went and looked up his test and counted the questions. There were 2 and he also swore he'd had 4-5. He was dumbfounded.
I'm telling you all of this because I don't want you to think that you should now go spend an enormous amount of time studying this area. These types are infrequent and also challenging - there are better places to spend your study time.
Okay, next. You ask how to improve your score by 10 points in a month. I'm guessing that's a typo - did you mean 100? Or wait - do you mean improve quant alone by 10 points?
That would be an increase of about 40 percentile points - that's an enormous amount for one month. Even if part of the problem was timing (not fundamental content knowledge), it would still typically take most people longer than a month.
It might be possible to raise your score 30-50 points overall in a month. For most people, an increase of 80-100 points would take more time.
Timing is clearly one issue. I'd like to get some more detailed data on your strengths and weaknesses in order to advise you further. Use the below to analyze your most recent MGMAT CAT(s):
http://www.manhattangmat.com/blog/index ... ice-tests/Then 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!)
For timing, start here:
http://www.manhattangmat.com/blog/index ... to-win-it/http://www.manhattangmat.com/blog/index ... nt-part-1/It typically takes about 4-6 weeks to address timing issues (longer if they are more severe), so get started on that today.
Also, I want to make sure that you're studying in the most effective / efficient way. Read this and pay particular attention to the "how to study" section:
http://www.manhattangmat.com/blog/index ... -the-gmat/