Hi Rohit,

Most of the time when we're publishing new editions of our books, we're just tweaking minor things: using slightly better example questions, tweaking the language to clarify, or fixing typos.

Sometimes we substantially restructure the way that we present information. Between the 4th and 5th editions, for example, we overhauled our 4-step process for approaching Critical Reasoning. None of the content had changed, just the way we presented it.

Foundations of Verbal has not changed substantially from the 5th to 6th editions. The book is really designed for English Language Learners, or those who had a poor foundation in grammar or reading. If you're already scoring a 36, I doubt that you need FoV. You probably need more practice in the medium --> difficult question range. What was your breakdown between SC, CR, and RC?

Advanced Quant has gone through a bit of reorganizing from 5th to 6th, but again the changes aren't substantial. Studying with the 5th ed would certainly give you a good foundation in how to attack difficult problems.

If you're scoring a 49... there's actually not much room for your score to improve on the quant! This is already a score that would seriously impress admissions committees - it's only 2 points away from perfect. Ignore the percentiles! You already have an almost-perfect score. Going from a 49 to 50 or 51 would help a little bit, but not nearly as much as gaining 3-5 points on the verbal side.

Let me know if you have any other questions. Good luck!