CAT hands out Percentiles to candidates instead of ranks. If you achieve a rank of 10000 among 2 Lac aspirants, you get a 95 percentile. Now, predicting the marks required to achieve this percentile depends on the difficulty of the particular CAT Attempt.
Following is a list of scores received in CAT 2016 and their respective percentiles.
As you can see, there isn't a huge difference in marks between 98.00 percentile and 99.00 percentile (14 marks i.e 5 questions). But there's a huge difference between 99.50 and 99.90 (i.e. 23 marks i.e. 8 questions).
Every says that CAT is highly unpredictable and you can't be sure about what percentile you are going to get. I think, Percentile system improves predictability to a huge extent. Irrespective of whether the paper is tough or easy, you'll get the percentile you deserve. Yes, its possible that if you make some blunder in 5-6 questions, it can drastically reduce your percentile. Nevertheless, someone who prepares for a 99.9 percentile won't get below 99.50 and someone who prepares for a 99 percentile won't get below 98 percentile.
Thus, there's a huge difference between preparing for a 98 percentile and preparing for a 99.50 percentile. Gaining an insight into which percentile you should aim for, could help you focus on what you should prepare for and what not to.
Even tough percentiles are used for shortlisting, never prepare for a specific percentile. You can't control your percentile, but you can control the score you'll achieve. Aim for a specific score.
Use this three step approach,
Research on the percentile that could get you into your desired colleges based on your profile. Even tough this is highly unpredictable, it gets you into a better position in respect to your mindset. You can get an insight about it here.
Once, you're sure about the percentile to aim for, find the score that's required to get that percentile.
Start preparations, and attempting mocks with that score in your mind.
Following is a breakup of the Sectional scores to target for the desired percentiles.
