Hi arnab275.
Your 720 total score is likely high enough for those schools, and Q47 is certainly acceptable. At the same time, Q49 may be more in line with what those schools want to see. So, since you've been scoring at that level, it may make sense to retake to eliminate any question in your mind regarding whether your score is what it needs to be.
If you do decide to retake, you could ensure that you score Q49 by working through quant one topic at a time and doing high accuracy untimed practice and
TTP Streaks Method practice as discussed in this post.
The Best GMAT Practice MethodsAlso, if you want some other ways to reduce the likelihood that you'll make careless errors, you could get some from this post.
Improving Your Accuracy on the GMAT