Hi neenpaques,
A 650 is a strong 'baseline' CAT score - raising that score to 740 will take some significant work though. Given these Scaled Scores, you have the opportunity to pick up points in BOTH the Quant and Verbal sections (although you'll likely find it easier to pick up the initial "block" of points in the Quant section).
A Q40 implies that you're still a bit unclear on certain Quant concepts, you're missing lots of 'strategy-based' points (especially in DS) and you're making little mistakes throughout the section. The V40 shows that you don't have any 'weak spots' in the Verbal section, so those missing points are more 'nit-picky' (and will likely be found once you learn to spot some of the more subtle wrong answer types that show up in the Verbal section.
1) What resources have you used so far?
2) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich