Hi qwerty12321,
A Q49 is a very strong Quant performance, even though it only ranks about the 80th percentile overall. It's a score that most Test Takers will never earn, so you have to respect that strong performance for what it is. While there's a reasonable argument to be made that anyone who can score Q49 should be able to score Q51, the difference rests primarily in two areas:
1) Absolute precision in your work, especially in DS questions. So you can't make any silly mistakes, your work must be super-organized, you can't have a pacing problem, you have to write everything down, etc.
2) Knowing all the "little things" when it comes to patterns, Number Properties, pattern-matching, using the answers to your advantage, etc. The Quant section is NOT a math Test, so you have to think beyond "just doing math."
Unfortunately, every Test Taker is susceptible to external stimuli. If you don't get enough sleep the night before your GMAT, your performance could be off. If you're slightly distracted by something at the Test Center or if you have a headache, then your performance could be off. If you're upset by dealing with the IR section....then your performance could be off. These represent some of the many factors that are out of your control.
This is essentially just a long-winded way of saying that you COULD have scored a Q51 right now, but you got a few questions wrong and it cost you just enough points to drop you to a Q49. Can you define the areas that you're not "great" at? Put some extra repetitions into those categories (and in DS, because everyone needs extra DS reps) and try to control as many of the "variables" of Test Day that you can.
GMAT assassins aren't born, they're made,
Rich
